Postwar Britain's nuclear deterrent was initially based on free-fall bombs deliverd by the V bomber force. It soon became clear that if Britain wanted to have a credible threat a ballistic missile would be essential. There was a political need for an independent deterrent, so Britain could remain one of the major post-war powers. The use of any American missile would have appeared to hand control to the US.
In April 1954 the Americans proposed a joint development programme for ballistic missiles, the United States would develop an ICBM of 5000nm range, the United Kingdom should develop with the United States support a MRBM of 2000nm range. The proposal was accepted as part of the Wilson-Sandys Agreement of August 1954 - which provided for collaboration, exchange of information and mutual planning of development programs. The decision to develop was influenced by what could be learnt about missile design and development in the US.
However doubts rose as the estimated cost rose, from the first tentative figure of £50m submitted to the Treasury in early 1955 to £300m in late 1959. The programme was crawling along compared with the speed of development in the US and the USSR.
Eventually the project was cancelled due to its lack of credibility as a deterrent. Before it had been made it was obsolete. Using a liquid oxygen-kerosine fuel and operating from fixed sites, meant that the delay in launch due to fuelling compared to probable warning time was too high for the missile to respond in time to a Russian attack. Also the Chiefs of Staff were unanimous that Blue Streak as a first fire weapon was unacceptable. Around £60m had been spent.
The government transferred its hopes to the Anglo-American Skybolt missile, before that too was cancelled and the British had to wrangle Polaris from the Americans. A brief attempt to salvage the Blue Streak for space research as Black Prince failed.