airliner and two of the current V bombers, the Avro Vulcan and Handley Page Victor. It was decided to use the Vulcan to initially carry two missiles each on hardpoints outboard of the main landing gear. Development and testing During development, it was decided that the system could not reach the required accuracy at the desired range without improvements to the guidance system. This led to the introduction of a star tracker platform that would enhance the existing inertial navigation system. The system had to be capable of tracking bright stars in direct sunlight, a challenging requirement. This change meant that the missile could only be carried in locations where the front of the missile could continually observe the sky. This had always been the case on the USAF's B-52 bombers, where they were carried under the wings, but presented a problem for some of the UK designs. Ultimately Skybolt was limited to the Vulcan, where its mounting points allowed the nose of the missile to project in front of this aircraft's delta wing. By 1961, several test articles were ready for testing from B-52s, with drop tests starting in January. 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. In Britain, compatibility trials with mockups started on the Vulcan. Powered tests started in April 1962, but the test series went badly, with the first five trials ending in failure. The first fully successful flight occurred on 19 December 1962. Cancellation By this point, the value of the Skybolt system in the US had been seriously eroded. The Polaris had recently gone into service, with overall capabilities similar to Skybolt, but with "loiter" times on the order of months instead of hours. The US Air Force was well into the process of developing the Minuteman missile, whose improved accuracy reduced the need for any bomber attacks. 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. He pressed for the cancellation of Skybolt as unnecessary. The British had canceled all other projects to concentrate fully on Skybolt. When McNamara informed them that they were considering canceling the program in November 1962, a firestorm of protest broke out in the House of Commons. Jo Grimond noted "Does not this