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Blue Peacock - Wikipedia, the free encyclopedia

One technical problem was that buried objects--especially during winter--can get very cold, and it was possible the mine would not have worked after some days underground, due to the electronics being too cold to operate properly. Various methods to get around this were studied, such as wrapping the bombs in insulating blankets. One particularly remarkable proposal suggested that live chickens should be included in the mechanism. The chickens would be sealed inside the casing, with a supply of food and water; they would remain alive for a week or so, which was the expected maximum lifetime of the bomb in any case. The body heat given off by the chickens would, it seems, have been sufficient to keep all the relevant components at a working temperature. This proposal was sufficiently outlandish that it was taken as an April Fool's Day joke when the Blue Peacock file was declassified on April 1, 2004. Tom O'Leary, head of education and interpretation at the National Archives, replied to the media that, "It does seem like an April Fool but it most certainly is not. The Civil Service does not do jokes."

The Blue Streak MRBM took at least fifteen to thirty minutes to load and fire, which made it less than entirely convincing as a deterrent.  

So Polaris, with US rocketry and warheads modified and built in the UK, was a reasonable deal.

Trident was an obvious continuation. The reality is that the UK doesn't have the skills needed to design effective warheads and missiles without US help, and can't afford an independent design program.