Critics of the change say it may damage the establishment's safety record, but the consequences of 'contractorisation' go much deeper. It may prove to be the beginning of the end for Britain's capacity independently to design and build nuclear warheads. This would be ironic: the change was inspired by Margaret Thatcher as a way of obtaining better value for taxpayers' money, but it may be the death of one of her other great passions, our independent nuclear deterrent.
Longstanding disquiet about the cost of Aldermaston was exacerbated during the Eighties by delays and cost overruns on the construction of buildings, which threatened to delay the Trident programme. Behind the issue of value-for-money, however, lies the problem of the nature of technical development; in particular, of who makes nuclear weapons policy.
There are two viewpoints: either nuclear weapons are produced simply as a response to political decisions; or inescapable developments in science and technology foist new weaponry on the politicians. The latter viewpoint was strongly expressed by the late Solly Zuckerman, who saw much of the nuclear arms race as a consequence of the activities of the weapons laboratories. When he was Chief Scientific Adviser to Harold Wilson, Zuckerman strove to block new weapons developments.
The Fifties and early Sixties were a 'golden era' for Aldermaston. After building the first atom bomb, rapid progress was made, in developing a hydrogen bomb, and in producing, with American help, light-weight warheads for the Polaris missiles.
The election of Harold Wilson in 1964 marked the end of this era. Although he backtracked on his earlier anti-Polaris rhetoric - he cancelled one submarine but continued the system's acquisition - Wilson agreed with Zuckerman that Polaris and the related WE-177 bomb design satisfied Britain's nuclear weapons requirements for the foreseeable future.
After the tests to 'proof' the Polaris design in 1964 and 1965, it was announced at the next 'stocktake' meeting - roughly annual UK-US nuclear co-operation reviews - that Britain had no further need to carry out nuclear tests. The effect on nuclear co-operation was dramatic. Almost overnight, British access to US weapons design information was withheld.
The tone of the British declaration clearly indicated to the Americans that no more British nuclear tests meant no more advances in British nuclear weapons designs. The nuclear design joint working group was suspended, and it did not resume its work until the UK developed a new warhead independently more than 10 years later. Other developments reflected the Government's desire to control Aldermaston. As part of the Ministry of Technology, it was directed towards work on civil technology, making a name for itself in artificial limb work, for example.
Concern about overstaffing and the general cost of the establishment led to an inquiry that resulted in the still secret Kings-Norton report. Then, in 1972, after almost 20 years of independence under the Atomic Energy Authority, Aldermaston was brought under the direct jurisdiction of the Ministry of Defence. The policy of appointing directors from within the establishment gave way to one of imposing career civil servants in the hope that they would be more responsive to the interests of Whitehall, and not of the nuclear scientists.
Despite these developments, Aldermaston continued to work on a new nuclear warhead that was eventually to gain political support, not least because of some key Aldermaston allies in Whitehall. This Chevaline 'modernisation' of Polaris was aimed ostensibly at enhancing the survival of warheads in face of Moscow's anti-ballistic missile defences, though some would say that enhancing Aldermaston's survival was a big consideration. British nuclear testing started again in 1974, and although cut off from American design work, Aldermaston was apparently able to validate a Chevaline warhead in the first three of these tests.
The Chevaline case suggests that too much discretion over research aims may have a Frankenstein effect: the creation of technologies that develop a life of their own. But Aldermaston's scientists would argue that it was only by anticipating demand for new technologies that they were ready to provide them when required.
Their worry today is that contractorisation will lead to over-rigid management. The new organisational structure, for example, is based on 'operations managers' achieving contractually defined goals, whereas Aldermaston used to be divided into sections based on professional expertise and geared towards pushing the 'state-of-the-art', facilitated by the relative (though decreasing over the years) discretion of the director to fund such research.
It could be argued that Aldermaston's traditional way of working was essential to the cultivation of expertise and innovation. Although patriotic zeal and personal pride may colour the picture somewhat, the impression given by participants in British nuclear weapons development is one of considerable achievements with limited resources.
With much less access to computer power and vastly fewer opportunities to carry out nuclear tests, Aldermaston was able to stay in the same 'ball park' as the American weapons design effort, which had two laboratories devoted to nuclear design alone, at least 10 times more personnel, the latest supercomputers and a programme at its peak of some 40 tests a year.
Design work at the US laboratories has typically proceeded through small, incremental change, each step accompanied by testing and computer modelling. Aldermaston's limited ability either to 'shoot or compute' has meant greater reliance on conceptual 'leaps' in designs. Whether such innovation would prosper under more rigid, less scientifically orientated management is doubtful.
Tighter Whitehall control over the weapons scientists is likely to stifle better understanding of nuclear weapons at Aldermaston. This may be no bad thing, because it is difficult to see what targets and what role exist for 'the deterrent' in the post-Cold War era.
If the plan to cancel the Tactical Air-to-Surface Missile is borne out, Aldermaston will have no requirement for a new warhead. At the same time, the rigid demands of managers may limit the scope of enthusiasts to pursue, and campaign for, their pet projects, and knowledge of how nuclear weapons work will dwindle as experienced designers leave.
Baroness Thatcher, one of the greatest nuclear advocates of recent times, may thus be remembered as having begun a process that may eventually lead to the loss of Britain's nuclear weapons capability.
The author works at the Research Centre for Social Sciences at the University of Edinburgh.