THE Union is on “red alert” with its “panicky flag-wavers plumbing new depths”, according to the SNP.

A party source was speaking to The National after Jackie Baillie, Labour’s deputy leader in Scotland, rounded on the BBC for employing a former submariner turned anti-nuclear campaigner as a senior script consultant on the naval drama Vigil.

The Sunday National yesterday revealed that Feargal Dalton, an SNP councillor in Glasgow and convener of the Nuclear Free Local Authorities Scotland Forum (NFLA), was brought in as a consultant on the drama, which centres around Trident nuclear submarine HMS Vigil.

Accordiing to the The Sunday Telegraph his appearance led to accusations that the BBC was creating a prejudiced and inaccurate picture of life on board the Royal Navy’s submarines.

It said as well as being a former Royal Navy Submarine Service weapons engineer, he is also a “long-standing supporter” of CND – the Campaign for Nuclear Disarmament (CND).

Dalton, who is married to SNP MP Carol Monaghan, retired from the Navy in 2010 with the rank of lieutenant commander.

Baillie told the newspaper: “Feargal Dalton has long campaigned against the Trident nuclear deterrent.

“The BBC should have employed an expert who, unlike Mr Dalton, is not so obviously biased against nuclear submarines and has a long standing association with CND.”

Vigil stars Suranne Jones as a detective investigating a conspiracy that threatens Britain’s nuclear deterrent.

Her character, Detective Chief Inspector Amy Silva, is sent to the fictional submarine to investigate a death on board shortly after the mysterious disappearance of a Scottish fishing trawler – the circumstances of which bear a striking resemblance to the sinking of the FV Antares by RN nuclear-powered submarine HMS Trenchant in the Firth of Clyde in 1990.

Silva’s investigations and those of her on-shore colleagues, bring the police into conflict with the navy and British intelligence service MI5.

The show also stars Martin Compston and Rose Leslie and is made by the team behind Line of Duty. Episode five airs tonight.

The paper quoted former LibDem leader Lord Ming Campbell of Pittenweem, a member of the House of Lords International Relations and Defence Committee, as saying: “I can understand why you might have someone opposed to Trident as an adviser for the peace camp scenes.

“But it would be strange if such an individual was giving advice about technical and on-board issues.

“The characterisation of the Navy and its ratings and officers in Vigil is a long way from the reality. The Royal Navy simply does not behave in the boorish way depicted.”

Royal Navy veterans were also said to be angry at the BBC’s decision to hire Dalton.

One former serviceman wrote on a Royal Navy personnel message board: “I’m sure the luvvies at the BBC are hand-in-glove with the CND-sympathising heads of the SNP on this piece of blatant anti-RN propaganda.”

Another said: “The script just makes the RN look terrible. I can’t believe the BBC are actually allowing the armed forces to be portrayed like this.”

A BBC spokesperson defended Dalton’s appointment, saying: “The World Productions team consulted a range of advisers and experts to make Vigil, including Mr Dalton who had no editorial input but offered factual insight from his long career as a member of the Royal Navy’s Submarine Service.”

An SNP source told The National: “The Union is on red alert, so no surprise its panicky flag-wavers are plumbing new depths.

"Targeting individuals who have expertise beyond politics and just because they’re SNP is simply pathetic.”