Mr Davies, in a scathing passage, detailed how this would be “clearly and unambiguously” against Treasury guidelines which require savings to be made in the current year rather than, hypothetically, at some point in the distant future.

The letter, written by Mr Davies to Defence Secretary Bob Ainsworth in explanation of his decision to turn down the QinetiQ proposal, destroys any suggestion that the decision was made only on socio-economic grounds in response to the Uist Task Force’s campaign.

It is confirmed that the consultants’ report, commissioned by the Task Force from Jane’s Advisory Services, was crucial in convincing Mr Davies that the proposal was deeply flawed on military grounds.

He wrote: “I think Jane’s comments should be taken seriously and the proposal should not go ahead unless we are satisfied with QinetiQ’s response.”

Mr Davies then made clear that he had no confidence in QinetiQ to maximise overseas use of the Uist range “and therefore contributions to overheads”. He also cast doubt on whether QinetiQ’s estimates of the costs involved in their proposal were adequate or if there was “underestimation of investment cost” thereby exposing the MoD to additional risk.

Mr Davies — who made a two-day visit to Uist — continued: “I was very struck during my many conversations with senior engineers and technicians in the Hebrides by the fact that none of them had had sight of the detailed proposals. I was able to identify from these conversations at least one understated investment expenditure which was acknowledged by QinetiQ management.”

The Minister added: “I fear that the lack of internal consultation involved in this process will inevitably increase the risk attached to the project — or in other words, that the assumptions made by QinetiQ are in danger of being less robust than they would be if full internal consultation had taken place.”

In another devastating passage, Mr Davies condemns QinetiQ’s failure to consider the “risk of not obtaining planning consent for their proposed dismantling of existing structures and building of a newÉ accommodation block on St Kilda”. Given the opposition to what QinetiQ were proposing, not least from the National Trust for Scotland, said Mr Davies, this approach appeared “excessively sanguine”.

Clearly having learned a great deal at first-hand from his visit, Mr Davies then turned to risk of disruption to the range if “local goodwill and support” were sacrificed through the planned job losses. There are, he noted, no bye-laws to protect the range; however the local population co-operates “willingly, indeed religiously”.

Mr Davies then asked: “Would that continue to be the case if the redundancy plans were implemented? Of course, I do not know. But it seems to me less than realistic not to even ask the question. When I raised the matter myself, I was told that just one recalcitrant fisherman could hold up a whole day’s firings at very great cost and with complete impunity.”

On the issue of local economic impact, Mr Davies noted that the jobs which would be lost accounted for around 10 per cent of those in full-time employment in the Uists and Benbecula. “There can be no doubt that the negative multiplier effect on the Hebrides would be substantial, though I have not seen any plausible attempt to quantify this.”

In the light of all this, Mr Davies concluded, “I have decided against the proposal”.

Councillor Donald John MacSween, a member of the task force, said: “The letter proves that the minister did give serious consideration to the submission from the task force and also the very flawed proposals from QinetiQ, which he comprehensively rejected. Great credit is due to the task force for assembling such a strong case in such a short time. The task force now needs to make sure that the future of the range is not embroiled in the Strategic Defence Review.

“The emphasis is on the Scottish Government to come up with a package of measures to diversify the Uist economy. It’s obvious this can’t be done by the existing agencies.”

Angus MacMillan, chairman of community landlords Storas Uibhist, added: “This information from Quentin Davies graphically shows the extent to which the proposal from QinetiQ was ill-considered and incorrect in all the aspects of  technical, finance and environmental considerations. The proposal was plainly not going to deliver any savings or improve the capability of the range.

“The community now hope that QinetiQ can work with all parties to ensure that the assets of the range and the islands can be explored to ensure maximum benefit to the defence and aerospace industries and therefore the island economy. We see this as an opportunity to move forward, secure the present operations and expand the facilities into other areas of associated work streams.”