On 29th December, 1940, the Luftwaffe kindled the Second Great Fire of London. The first sirens sounded at 6.17pm and the last bomber cleared the City at 9.30. For three and a quarter hours incendiary and high explosive poured down onto the square mile that is the City – that is the heart of London.

By eight o’clock, when it was evident that the very centre of our Capital could be lost, the order went out from the Prime Minister’s Headquarters, sixty feet below Whitehall that whatever else, St Paul’s Cathedral had to be saved. Fifteen firemen paid with their lives to win that battle, but in the morning, when the smoke cleared, there was the dome of St Paul’s, surrounded on all sides by devastation, but still there. From the top of the Daily Mail building, probably the most famous newspaper photo ever taken was snapped. That picture became the symbol of Britain’s defiance, and the people’s determination to fight on.

Two days later, when the English newspapers arrived in Berlin via the German Embassy in Dublin, Hermann Goering made his Fuehrer a promise. That St Paul’s would be destroyed at whatever cost.

The method employed to achieve this end would be the X Verfahren radio navigation system. This consisted of a radio beam sent from a transmitter located on the Cherbourg Peninsular. The pilot of an incoming bomber could pick up an audible signal through his headphones, and would fly along the beam until the note changed radically. This was caused by an intersecting transmission beamed from Emden on the northwest coast of Germany. The beams would cross above the target, which meant that the bomb aimer did not need a visual fix to bomb accurately.

Luftwaffe radio technicians were satisfied that the radio beams were intersecting right above St Paul’s Cathedral, but time after time photo reconnaissance would show that although the area to the north and east of the building was devastated, the great dome itself was virtually untouched. Repeated attempts by the cream of Luftflotte 3 pathfinder squadrons failed to achieve the desired result

The second week in January saw a technical advance for the Luftwaffe – the advent of Y Verfahren. This not only gave a more definitive sound signal to the pilots and bomb aimers, but it incorporated a narrower beam and gave a warning five seconds before the intersection point.

Otto Bernard, Staffel Kapitan of KGR 100 Pathfinders, reckoned he knew the way to destroy St Paul’s. In lengthy consultation with his Group Commander, Chief Armourer and Intelligence Officer he persuaded them to sanction a special mission.
In the last five months, since the start of the London Blitz, a secondary and little publicised battle had been joined.

Luftwaffe High Command, under the specific direction of Reich Marshall Goering, decreed that ten percent of high explosive bombs should be equipped with delayed action fuses. The effects of these were two fold. Firstly, an unexploded bomb meant that whole areas of the City were paralysed whilst it was defused. Roads and railway lines were closed, fractured water mains and electricity lines remained unrepaired until the menace could be neutralised. There was another effect. One that was unquantifiable. Fear. One never knew how large the unexploded bomb was, therefore how big an area had to be evacuated around the site.
Most sinister of all, one never knew for how long the fuse was set.

On the British side were the bomb disposal squads, who nightly faced death at close quarters, in claustrophobic and often waterlogged craters.

When the Blitz started in September, the fuses were most often set to explode twelve hours after impact. The thinking of the Luftwaffe strategic planning group was that if the British simply evacuated the area surrounding the bomb and waited for the explosion, then the disruption went on for a long time.

They underestimated the courage of the Royal Engineers, and Royal Navy teams, charged with defusing the bombs and the parachute mines.
As these men became familiar with the thinking patterns of the opposing personnel, the success rate and speed of defusing increased. Then came the trembler fuses – where a phial of acid would break as the bomb landed – and eat away at the stabilising mechanism of the fuse. By the time the potential de-fuser was ready to manoeuvre the bomb into a position that would enable him to get to the fuse plate – the slightest movement would trigger the detonator.
By the middle of January 1941, the Germans had decreased the fuse times to fifty minutes. Just long enough for the teams to evacuate the area and get their equipment in place, whereupon the bomb would detonate.
The battle within a battle had become personal.

In a specially reinforced hanger at Le Bourget, Otto Bernard worked with his chief armourer on his Heinkel 111. If his plans were to come to fruition, the bomb gantry had to be elongated and reinforced. From the bomb magazine, they had extracted one of the new SC2500 high explosive devices, and mounted it on a test bench. Then an aluminium sleeve was mounted over the fins and extended for two metres
behind the bomb. Into this sleeve they introduced a, relatively small, but similar diameter, 500kg high explosive bomb. The sleeve was meant to collapse on impact leaving the two bombs separated, the smaller behind the larger in the same crater.

Whilst his armourer was wrestling with the technicalities, the Staffel Kapitan was poring over a blueprint of St Paul’s Cathedral. A slide rule and protractor were brought into play as he covered his pad with calculations. When he was satisfied with his attack plan, there was another long meeting with his Group Commander, at which time the strategic objectives of his mission were agreed. Not that he had any say in these aspects of his target – this was the job of his intellectual superiors and he knew better than to question their decisions.

One of the other Staffel Kapitans told Otto that he had overheard a snatch of telephone conversation between their Group Commander and the Head of Luftflotte 3, Feldmarschall Hugo Sperrle himself. Otto had no doubts about how much was hanging on this venture.

When all the foreseeable complications had been ironed out, the date was set.

At 2018 hours precisely on the night of Saturday, 25th January 1941, Otto Bernard’s Heinkel 111 took off from Le Bourget and set course for England. Over the Channel he picked up the Cherbourg transmission beam and followed it towards the enemy coast. The Luftwaffe would not be operating over London that night, so Bernard did not have to worry about collisions with other raiders. As predicted by his meteorologist, cloud was ten tenths, so the London Searchlight teams would not bother him either. Equipped with the brand new Y Verfahren, there would be no problems with navigation.

At 2037 hours British Radar detected the incoming hostile aircraft and the sirens sounded in a line along the course of the intruder from the south coast to the southern approaches to London.

Four kilometres short of his target he hit the Emden beam and turned on a predetermined course northwest. Flying at precisely 380kph at a height of 3,690 metres the Heinkel closed upon its target.

2nd Lieutenant Alexander Campbell of the Royal Engineers had been roused from his bunk when the air raid sirens sounded. Now he was assembling his bomb disposal team for the night’s work. He had been on duty for thirteen consecutive nights and was well aware that in his line of work fatigue could kill him. For a minute he allowed himself to think about his wife and six weeks old daughter, hopefully asleep in their beds. He was not a religious man, but as always when the sirens went, he intoned a prayer that he would be allowed see them again. He had never told Ruth what his job entailed – he saw no sense in worrying her unduly.

Otto Bernard opened the bomb doors of his Heinkel. The radio operator counted down the seconds on his stopwatch and the bomb aimer pressed the release. The aircraft leapt as the heavy load left its fuselage. Otto closed the bomb doors with one hand and wrenched the control column hard left with the other. He was well aware that having to maintain a straight line for his bombing run made him vulnerable to marauding night fighters. No sign of the RAF tonight though.

As they turned for home he allowed himself a grin. He had a strong feeling that tonight’s work would earn him a Knight’s Cross with Diamonds, the highest battle honour bestowed on its warriors by the Third Reich. And always presented by the Fuehrer himself. That would be a story to tell his grandchildren.

One hundred yards from the south entrance to St Paul’s Cathedral, Warden Stan Wilkinson heard the whistle of a descending bomb and threw himself flat on the pavement. He heard the impact quite plainly and with his hands covering his ears he rolled into as tight a ball as he could manage, and waited for the inevitable explosion. And he waited. After the longest ten seconds of his entire life, he raised his head and looked towards the Cathedral. As best he could make out in the murky light of the blackout, there was a hole by the side of the steps leading to the south transept. Clutching his shaded ARP lamp, he sprinted over to the hole. The crater appeared to be about three feet in diameter and disappeared, at an angle, deep beneath the foundations of the building. He had seen enough in the last four months to know that this was an unexploded bomb. He ran back to his post, grabbed the phone and asked the operator to connect him with the Incident Room.

Within ten minutes the unmarked van bearing Alexander Campbell and his team arrived. At least the warden was able to verify the impact time at 2058. On recent form the officer had about thirty five minutes to make the bomb safe. Having set up his team and started the generator, Campbell put on his miners helmet and lowered himself into the crater. Wriggling deeper and deeper into the tunnel left by the bomb and expecting to come across the tail fins at any moment, he was amazed how far the missile had penetrated. Campbell estimated that he was about ten feet below the floor of the crypt when he finally found his objective. It was a one thousand pounder and he could hardly believe how far it had burrowed its way under the Cathedral. Taking his excavating tool from his belt, he started to clear the soil from one side of the bomb. He was lucky and located the fuse plate almost immediately. He checked his watch. 2133. There appeared to be the remains of some sort of metal sleeve around the nose of the bomb – perhaps this was a new device to obtain deeper penetration when the weapon landed. He made a mental note to report this anomaly to his boss.

If it had a fifty minute fuse there was only about fifteen minutes left.
Not enough time – not nearly enough time. He had to back out and get his team clear.

As he wriggled backwards towards the mouth of the crater, his mind was working overtime. He was as aware as anybody how important the destruction of the Cathedral was to the Germans – and its preservation to the morale of the British People. He could not be sure how much havoc the 500kg bomb would cause if it exploded. It would certainly destroy the crypt and most probably the high alter would topple into the crater. Whether the foundation stones of the walls supporting the great dome would be sufficiently weakened for it to collapse, he could not know.

As he reached the entrance to the crater and stood up, his mind cleared. Now he knew what he must do.
First, he assembled what he would need by the side of the crater. The generator could be left running and would power the powerful electro magnet and his trepan cutter. Then the rest of his team were ordered back to the safety of the heavily sandbagged ARP post.

‘Once more into the breach dear friends’ he thought as he lowered himself into the crater. As he reached the waiting bomb he checked his watch again. If it was a fifty minute fuse, he had about three minutes before detonation. He retrieved his stethoscope from his belt, attached them to his ears and placed the trumpet carefully on the fuse plate. The clock was still ticking. No time to mess about – he reached behind him and pulled forward the electro magnet attached to the heavy duty lead. The vibration assured him that the generator was still running, and he quickly clamped the clock stopping magnet to the side of the bomb just above the fuse plate and switched on. Another check with the stethoscope and his heart sank – the clock continued to run.
He didn’t have time to get out now so he took a deep breath and evaluated his situation. Since the Blitz had started the attrition rate amongst bomb disposal officers was one in three. OK. If it was to end here he might as well die trying.

He removed the failed clock stopper and pulled up his trepan cutter. He started the tool and began to cut around the fuse plate. After five minutes work he had to tie his handkerchief around his forehead to stop the sweat running into his eyes. Finally, the cutter had completed the circle and he was able to remove the relevant piece of bomb casing. As far as he knew the Germans did not employ trembler fuses on anything smaller than 1000kg bombs, and so it proved with this one. When he had cut the wires to stop the clock and removed it from its mounting, he was amazed to see that the fuse still had thirty-five minutes to run. Almost as if the Germans wanted him to have time to defuse it. He dismissed this thought from his mind and crawled backwards out of the tunnel.

He was very happy to allow his number two to attach a harness to the now harmless bomb, and withdraw it from its hiding place.
He and his team took their bomb to the controlled explosion site on the outskirts of London. Then it was time to go to the pub to celebrate 2nd Lieutenant Campbell’s escape from certain death.

One thing was certain. Neither Campbell nor his number two had really taken it in that the entry tunnel for the bomb ran beyond the site of the weapon they had removed.

About that time Otto Bernard was being debriefed by his Group Commander and intelligence officer. From everything they knew, the mission had gone perfectly. The 500kg bomb would have been safely defused by now and the 2500kg monster would be waiting in its lair beneath the great dome of St Paul’s Cathedral. It had been set with a fourteen hour fuse. Timed to explode just as the 11 o’clock service started on Sunday morning. They had no doubt that, not only would the dome of the Cathedral collapse into the crater, but at least three hundred worshippers would die in the ensuing carnage.
One thing they did not know. When the double bomb had penetrated the concrete apron surrounding the historic building, the clockwork fuse had been partially dislodged from its gimbals. It did not run.

As a result of his selfless bravery in the execution of his duty, Alexander Campbell was awarded the George Cross. Against all the odds, he survived the war. He and his wife Ruth bought a small cottage in Somerset. He never told his wife about that terrible decision he had to take on a January night in 1941.

Otto Bernard never received his Knights Cross, and in 1944 failed to return from a mission on the Eastern Front.

David Morgan ran down the steps of the crypt, following the tour guide.
That Saturday morning, David and his wife were amongst the dozens of visitors who marvelled at the architecture of Sir Christopher Wren, and the strange acoustics of the Whispering Gallery. They had stood reverently in front of the graves of England’s great heroes, Wellington and Nelson enshrined within their stone edifices in the crypt.
It was at that point that David’s wife, Samantha, felt her slightly too big wedding ring slip off her finger, and with unerring certainty, disappear down a crack between the flagstones.
With some trepidation, David had spoken to successively higher ranked officers of the church, until at last he stood before the Dean himself. His request was quite unprecedented. He wanted to use a metal detector to locate his wife’s precious ring. The Dean was a