In 1940, one of the Navy's few means of detecting German E Boats was listening to their radio transmissions.

Much of this was done by WREN linguists on shore, but some ships carried German speakers on board.

One of them was the Hunt Class destroyer HMS Cotswold.

Cotswold's linguist was an exiled German Jew known to her crew as Wolfgang, whose hatred of the Nazis kept him at his post through long and mostly uneventful patrols.

His English was relatively basic, but he had an academic's attachment to precision in his translations.

One night Wolfgang diffidently announced that he could hear German voices on his monitoring set.

The Officer of the Watch was concerned to know what they were saying, and to know that (in the words of Father Ted) quite fast.

Wolfgang could not be hurried.

'It is about...torpedoes. I think...yes...he says 'prepare to fire.'

Consternation on the bridge. Urgent helm and engine orders.

Amidst all this, Wolfgang recurred.

'I think...it is not 'prepare to fire'...'

Slight relaxation on the bridge. Signs of relief on the skipper's face.

'...it is in fact 'fire now''.

Cotswold threw herself wildly about the sea and fired vast quantities of star shell in all directions.

Once more, Wolfgang called the bridge.

'The swearing is very bad. They say 'The enemy is awake. Stop the attack.''

A vastly relieved Officer of the Watch told Wolfgang he'd saved the ship. Which Wolfgang did not understand.