Staff levels at the Atomic Weapons Establishment (AWE) at Aldermaston and the warhead assembly plant at nearby Burghfield rose from 3510 in 2004 to 4620 in February this year as part of a recruitment drive targeting physicists and researchers.
The Government has also earmarked Â£5.7bn over the next three years for improvements at both sites and work to maintain the existing weapons stockpile, believed to be about 160 warheads.. The aim is to produce warheads which contain fewer degradable components, giving them a longer shelf life, and to make them so dependable that none would have to be detonated in an underground explosion that would contravene the worldwide Test BanTreaty in place since 1998.
The UK is meanwhile in the process of investing almost Â£2.2bn in the Aldermaston site to equip it with a state-of-the-art Cray supercomputer codenamed Larch and a laser codenamed Orion to help model nuclear explosions in place of live testing.
John Ainslie, Scottish CND's co-ordinator, said: "A lot of money and research is going into the design of the warheads, no matter what is said in Parliament."