Andrew is all at sea over officer and a hero role

The 31-year-old star of Garrow’s Law and The Fixer — who has just appeared as Joseph in the BBC’s adaptation of The Nativity — will be making the ladies swoon as he dons a ship’s officer’s uniform to play Thomas Mortimer, the seaman who risks his life to save others aboard the British war ship RMS Laconia.

The dramatic show will be aired on BBC1 at 9pm on January 6. It re-enacts the events of September 12, 1942, when the RMS Laconia was torpedoed and sunk by a German U-boat.

However when U-boat Commander Werner Harten-stein realised the people in the water were civilians, he defied the Nazi High Command and ordered his crew to save as many of the shipwrecked survivors as possible. It is a huge, huge epic tale,” said Buchan, who attended Rivington and Blackrod High School before training at RADA.

“This actually happened, where an English passenger liner called the Laconia got torpedoed by a German U-boat because the Germans thought it was carrying troops. And then the captain of the U-boat realised it was just carrying civilians and he ordered a full rescue against the wishes of his boss on land.”

Hartenstein then gave orders for messages to be sent out to the Allies, so they could organise a rescue of the survivors.

But things went from bad to worse when the U-boats were spotted by an American B-24 bomber, which mistook them for a legitimate target, and moved in to attack.

“The cast were unbelievable,” said Buchan, who is full of praise for his co-stars.

“It was a co-production between England and Germany. Half the cast were German, so you had these bizarre scenarios.

“There was one day when I was on set with eight Germans, and the German director, who all spoke English for my benefit.

“I think that is unbelievable, rarely would you find nine Brits in a room with one German and the British all speaking German. It was an amazing project to be a part of, one of the biggest I've done so far.”

l Laconia is on BBC1, Thursday, January 6, 9pm.