DEFENCE Secretary Malcolm Rifkind is being warned forcefully by

Scottish peers on all sides that his decision on the future of Rosyth

dockyard is political dynamite.

Their campaign built up over last weekend and took on a new urgency

after the System Three Herald poll revealed the fragility of the Tory

position in Scotland.

Mr Rifkind is receiving a series of letters from up to 30 influential

and active Scottish peers who are pointing out that Scotland cannot be

expected to provide a home for decommissioned nuclear submarines like

Polaris if the Trident maintenance contract does not go to Rosyth.

Their letters have been copied to Sir Michael Hirst, the new Tory

chairman in Scotland, and to Mr Richard Ryder, the Government Chief

Whip. The Government is expected to be questioned on the issue in the

Lords on June 7, although Mr Rifkind's final decision is not expected

until July.

The peers are quoting repeated assurances in the 1980s on Rosyth's

long-term future from Government Ministers such as Mr Michael Heseltine,

Mr Norman Lamont, and Mr George Younger, when they were fighting off the

CND case for ridding Scotland of the hazards of nuclear weapons and

vessels.

In a Lords debate in February, Lord MacKay of Ardbrecknish, the former

chief executive of the Tory party in Scotland, won acclaim when he said:

''One does not have to get up very early in the morning to realise that

the anti-nuclear campaigners will quickly have a slogan: 'If we cannot

have your living submarines, we do not wish your dead ones.' ''

The peers' message is designed to be conveyed to the Prime Minister in

the belief that the rival bids of Rosyth and Devonport are now so close

that Scottish political considerations in the light of previous

ministerial promises must be met. They believe that, while some Tory

seats may be endangered in the south-west of England if Devonport fails

in its bid for Trident, the future of the Union could be at stake if

Rosyth loses.

Yesterday, the System Three-Herald poll indicating that more than 80%

of Scots favour devolution or independence, appeared to add weight to

this argument. Scottish Tories at Westminster believe that Ministers are

looking at the respective savings involved in the Rosyth and Devonport

bids over a 15-year period. Rosyth is said to be the more attractive

proposition over the first five years.