The basic concept was to allow US strategic bombers to launch their weapons from well outside the range of Soviet defenses, as much as 1,000 miles (1,600 km) from their targets.

This was a heavier warhead and would reduce the range to about 600 miles (970 km), meaning the bombers would have to cross the Soviet coastline to attack Moscow.

These failures, along with a lack of mission after the successful development of submarine-launched ballistic missiles (SLBMs), led to its cancellation in December 1962.

This was resolved by a series of meetings that led to the Royal Navy gaining the UGM-27 Polaris missile and construction of the Resolution-class submarines to launch them.

The US had been developing its own ICBMs as well, but early models, like the SM-65 Atlas, required some time to prepare to launch from their surface launchers and were vulnerable to sneak air attack.

The Polaris equipped submarines could cruise in large areas of the Atlantic or Pacific where the Soviet fleet was unable to find them, and launch their missiles with impunity.

This fact was more worrying to the Air Force than the Soviet arsenal and generated a number of internal reports on how to deal with this threat to their dominance in the strategic field.

At the same time, the Royal Air Force (RAF) was having problems with their MRBM missile project, the Blue Streak, which was long overdue.

No fixed land-based missile system could be credibly installed in the British Isles; they were well within the range of Soviet air strikes.

The limited land mass available meant it would be relatively easy for missile sites to be spotted no matter what security measures were taken, and flying time for a jet bomber from the coast to any potential inland location would be on the order of minutes.

While capable, the missile flew at altitudes and speeds that left it vulnerable to improving SAMs, and it had a number of reliability and serviceability issues that made it less than ideal.

[4] Avro was made an associate contractor to manage the Skybolt program for the United Kingdom and four different schemes were submitted to find a platform for the missile.

[4] A number of different aircraft were considered, including a variant of the Vickers VC10 airliner and two of the current V bombers, the Avro Vulcan and Handley Page Victor.

As Valiant had limited range, the decision was made to move forward only with Vulcan, where its mounting points allowed the nose of the missile to project in front of this aircraft's delta wing.

In January 1961 a Vulcan visited the Douglas plant at Santa Monica, California, to ensure the modifications to the aircraft were electrically compatible with the missile.

Robert McNamara was particularly opposed to the bomber force and repeatedly stated he felt that the combination of SLBMs and ICBMs would render them useless.

Over the next few days a new plan was hammered out that saw the UK purchase the Polaris SLBM, but equipped with British warheads that lacked the dual-key system.

The current position was constantly updated from the host aircraft through accurate fixes, meaning that the accuracy of the platform inside the missile was not as critical.