It was Walker who had corrected the first major blunder at the cathedral - a mistake which would have had disastrous consequences if it hadn’t been for his bravery.

Incredibly, the Normans built the east end of the great structure on top of a stream, resting the great stone walls on beech trees, which were simply laid side-by-side over the water.

The building showed signs of subsidence from the very start, and by the end of the 19th century, a collapse seemed inevitable.

Desperate times called for desperate measures, and after uncovering the foundations and learning the awful truth about their inadequacy, a team of engineers led by Sir Francis Fox decided to send a diver into the mire to put things right.

And so it was that the diver William Walker donned breathing apparatus and, working in zero visibility, began removing mud from the 14-foot (four-metre) void and replacing it with bags of concrete.

George V awarded William Walker a Member of the Royal Victorian Order (MVO) and declared him a hero. In 1919, the diver died in a flu epidemic. His story was forgotten until 1956, when the BBC celebrated the 50th anniversary of his achievement with a radio programme.

The renewed interest soon sparked calls for a memorial in the cathedral and a statue was first commissioned from local sculptor Norman Pierce. However, after a change of mind, the commission was then handed to Sir Charles Wheeler, president of the Royal Academy.

But when Sir Charles’s statue was unveiled, Walker’s relatives were astonished to see, not the familiar face of William, but that of the engineer, Sir Francis Fox. The sculptor, it turned out, had been given the wrong photograph to work from.

It was almost five decades before the embarrassed cathedral authorities could be persuaded to do something about it. In 2001, a new statue of William Walker, by the sculptor Glynn Williams, was placed in the building that, in the words of George V, the diver had saved “with his own two hands”.