AN HISTORIAN has challenged a recent claim that a German submarine penetrated the River Clyde high security zone during the Second World War.

Port-born ex-BBC Scotland sports commentator Alastair Alexander, who wrote a book about U-boat warfare on the Clyde, insists that there was no breach and that official documents prove this.

Mr Alexander dismissed the new version of events reported in ‘The Mystery of U-33: Hitler’s Secret Envoy’ by Nigel Graddon who said he had obtained fresh evidence that the U-boat got through the Cloch boom defence netting between Gourock and Dunoon in February 1940.

Mr Graddon’s reprinted book includes evidence from the family of one of the survivors.

But Mr Alexander dismissed this as ‘hearsay’ and said that documents from the government’s National Archive show conclusively that U-33 was sunk off Arran and did not get anywhere near the Cloch boom.

He said: “It is a recorded fact that U-33 was the first-ever submarine to be detected and sunk using ‘Asdic’ sonar detection.

“This was carried out by HMS Gleaner during its regular patrol off Arran on 12 February.

“Gleaner detected the conning tower at 3.53am and attacked the U-boat.

“Further attacks are recorded at 4.12am and 4.40am, and the submarine sank at 5.31am.” Mr Alexander, who was born at Parklea Farm and brought up at Margaret Street in Greenock, said there was also a top secret ‘Asdic ring’ on the Clyde which would have detected U-boats approaching the Cumbraes.

He said: “It’s important that the historically accurate facts are known about this sinking.” Mr Alexander said it was wrong of Mr Graddon to say that survivor Hans-Joachim Ehrhardt was rescued from the water by a Leading Seaman P. Green, as claimed by Ehrhardt’s family.

Mr Alexander said: “The archive documents clearly show that P. Green, was, in fact, the person who interrogated Ehrhardt after he was rescued.” Mr Graddon had said that local people vividly recalled how ‘all hell was let loose’ on the night U-33 allegedly got through the barrier.

But Mr Alexander said this activity could have been unexploded bombs being detonated.

He added: “The Queen Mary and Queen Elizabeth were visiting the Clyde every fortnight during this period.

“The security was fantastic.

“No German submarine got through the defence boom.”