DOWNING Street has quickly snuffed out any idea that the UK Government is examining the possibility of designating the Clydeside home of the Trident nuclear deterrent as sovereign United Kingdom territory should Scotland vote for independence next year.

David Cameron's spokesman said: "This Government has not commissioned contingency plans over Faslane. No such ideas have come to the Secretary of State or the Prime Minister. They would not support them if they did. It's not a credible or sensible idea."

This came a few hours after the Ministry of Defence said: "The sovereign base area is an option."

It has been suggested that when stories began to break about the sovereign base idea, leading anti-independence campaigners swiftly contacted Downing Street to see what was going on, realising this would provide the Nationalists with more ammunition to fire at them. By the morning, No 10 had firmed up its denial.

The issue of making Faslane part of a UK sovereign territory post-independence was first mooted last September.

Professor William Walker, from the School of International Relations at St Andrews University, told the Commons Scottish Affairs Committee the sovereign base idea would involve not just Faslane and Coulport but also Dounreay, which is used for testing submarine reactors.