CANCELLING Britain's nuclear deterrent would save taxpayers almost £84 billion over the next 50 years and could result in the loss of up to 30,000 jobs – many in Scotland.

A new study by Professor Keith Hartley, a leading defence economist, and published by the think-tank, the British American Security Information Council (Basic), explains the UK Government needs to make a decision to proceed with a replacement for the four submarines based at Faslane on the Clyde by 2016 – the so-called "main gate" decision.

The three main parties at Westminster are committed to a submarine-based deterrent although the Liberal Democrats insist cheaper options exist.

While David Cameron is firmly in favour of retaining a submarine-based nuclear deterrent, his views in the run-up to 2016 might be influenced by the Trident Commission organised by Basic, headed by the seasoned politicians Sir Malcolm Rifkind, the former Conservative foreign secretary, Lord Browne, the former Labour defence secretary, and Sir Menzies Campbell, the ex-Liberal Democrat leader.

Given the £38bn black hole in the MoD's budget, the Prime Minister might be willing to consider cost-saving alternatives.

Prof Hartley, Emeritus Professor of Economics at the University of York, says: "Without a Trident replacement there will be serious questions about the future viability of the UK submarine industry. Without alternative warship building work, then Barrow-in-Furness and other areas such as Aldermaston and Plymouth need appropriate Gov-ernment adjustment policies."

The report notes naval and civilian personnel number around 6500 on the Clyde and refers to how Glasgow already suffers from high unemployment, which suggested "limited prospects for alternative employment" should Trident not be replaced.

It stresses how without a Trident replacement, there would be job losses affecting both military personnel and civilian staff but says: "Glasgow is part of the wider Clyde economy where there are alternative job prospects and the unemployment rate for Scotland is similar to that for Great Britain."

The SNP Government has made clear an independent Scotland would not have weapons of mass destruction on its soil. The UK Government has admitted it has no contingency plans for its nuclear deterrent base on the Clyde should Scots vote for independence.

Prof Hartley's report has only one brief note about the possibility of Scottish independence, which says: "If Scotland votes for independence, there might be questions about the future of the warship yards in Scotland.

"Current MoD policy favours retaining a UK warship building industry, including submarine construction. Scottish independence might mean future warship building is undertaken in English shipbuilding yards such as Barrow and Portsmouth."

Last night, Angus Robertson, for the SNP, told The Herald: "This report confirms nearly £100bn could be saved by cancelling Trident. Faslane has a great future as a conventional naval base in an independent Scotland. A yes vote in the referendum would be the best way to ensure we rid Scotland of Trident."

However, Thomas Docherty, for Labour, insisted: "In a separate Scotland, the MoD would not award defence contracts to a foreign country at the expense of yards in Barrow and Portsmouth. Separation would be the deathknell of Scotland's shipyards."

The Trident replacement submarines are planned to enter service from 2028 and, with a service life of 25 to 30 years, will remain operational into the 2060s. The acquisition costs of the replacement are estimated at up to £25bn for a four-boat fleet with annual running costs of £2bn.

The report points out how there will be a further £2.2bn cost from maintaining and extending the existing Trident fleet until replacement submarines are in service. Plus it is likely there will be "hidden costs" of the Trident replacement, which will only emerge at some future date; for example, there are the costs of replacing the Trident missiles after 2042. Some £4bn costs have already been incurred in the so-called concept and assessment phases, which run up to the "main gate" decision of 2016.

Prof Hartley pointed to 2006 figures showing Glasgow has 11 firms, more than any other town or city in the UK, supplying the nation's submarine industry, with Aberdeen on 12.

The professor adds of Glasgow: "Without a Trident replacement, there will be job losses affecting both military personnel and civilian staffs. The military employment contract means that Royal Navy personnel employed on SSBNs [sub-surface ballistic nuclear submarines] are more easily reallocated to alternative Navy jobs. Their contract requires that they obey orders and the Navy will provide appropriate re-training.

"The cancellation of a Trident replacement will mean the loss of some civilian jobs at HMNB Clyde; but Glasgow is part of the wider Clyde economy where there are alternative job prospects and the unemployment rate for Scotland is similar to that for [the rest of] Great Britain."