Up to 600 dockyard workers are to lose their jobs at Devonport as Babcock International confirmed that the number of submarine programmes that it was working on would be halved this year.

Babcock Marine bought Devonport, Plymouth's biggest employer, in June for £350million, but the yard has been bracing itself for job losses since 2005 when DML, the previous owner, predicted a downturn in submarine work.

The replacement of Trafalgar class boats with the Astute, which does not need refuelling, has had a big impact.

When the refit of HMS Triumph is completed this year, Devonport's main role will be refitting Trident submarines and other naval work that it shares with the Babcock dockyards Faslane and Rosyth in Scotland.

Devonport employs about 4,300 people, but two decades ago that figure was 13,000. The company hopes to keep compulsory redundancies to a minimum, but it is under pressure from unions to axe contractors first. It is thought that about 500 Devonport workers are short-term contractors.

The shortage of submarine work is forcing defence contractors to consider alliances, similar to those being forged for surface war ships.

The submarine alliance will encompass Babcock, BAE Systems and Rolls-Royce. In exchange for the industry agreeing to collaborate, the Ministry of Defence will sign a “terms of business agreement” that will set out roughly what work it will fund over the next ten to fifteen years.

Devonport dates from 1691, when William of Orange commissioned the building of a dockyard to support

the Royal Navy in the Western Approaches. The MoD recently spent £900million upgrading the facilities used to refuel and refit nuclear submarines and a spokesman said: “MoD will continue to work closely with Babcock Marine to devise an optimum programme of submarine and surface ship work to maintain a valuable skills base.”

A spokesman for Prospect, the union, was hopeful that work could be transferred from other Babcock yards to preserve Devonport jobs.

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