Getting to the HMS Invincible.
In 1960 the RN Director of Plans began a series of studies of ships to replace the then authorised 5 cruisers, the main aim being to allow command for independent operations and also free space on carriers by having the large ASW helicopters and an area defence SAM system. Studies 6-9 were to destroyer standards and Study 21 to cruiser standards with Grade II flagship facilities. Studies 6-9 of 1960 looked a fair bit like contemporary Italian helicopter/SAM cruisers; 430-485' long and 5400-6800t with 45-6 Wessex helicopters Study 21, which culminated in Study 21M3 in March 1961 had a through-deck, Sea Slug SAM, twin 4.5" gun turret, 2 x quad Seacat SAM and 9 Wessex helicopter on 11,800t and 570'. It was thought that these ships could provide area SAM coverage and the final 4 County class DLGs would be delayed to build 4 of these ships, they would have the 988 Broomstick radar ADA/TIDE command facilities and cost 16.7 million pounds; this was the plan up to 1963 for ships to enter service in 1969-71.
In 1963, after rejecting a proposal for more helicopter training ships like HMS Engadine, it was decided to convert two Tiger class cruisers to be in service by 1966 and defer the ordering of the Escort Cruisers until 1969 when they could be equipped with the Sea Dart SAM. Blake entered refit in April 1965, work was halted during the 1965 Defence Review, restarted at reduced speed in March 1966, specification changed in in early 1967, caught fire in January 1969 and finally completed in April 1969. The Lion was placed in reserve in January 1966 and the Tiger laid up for preservation in December 1966 for her refit in July 1967, which took until July 1972 and cost over 13 million pounds on the original 5.4 million pound estimate. Virtually nothing in the original estimates back in 1963 proved to be correct in practice, however these conversions effectively killed the 'Escort Cruiser' concept.
In the meantime the CVA01 carrier, costed at 70 million pounds in January 1966, was cancelled in April 1966 and HMG announced the rapid rundown of the carrier force by 1972. In 1967 the Ark Royal went into refit for Phantoms which was presumed to be short and cheap to allow her to run to 1972. In the end this refit took 3 years and cost 32 million pounds. In 1970 the new Conservative Government reversed the Labour decision and prolonged the life of the Ark until 1978.
In 1966-67 in the wake of the cancellation of CVA01 and announcement of the rundown of the carrier force the RN successfully argued that a ship was needed to command the future destroyer/ frigate Maritime Contingency Forces (MARCONFOR), whether or not such a ship carried helicopters. One reason HMS Bristol was built after the cancellation of the carriers was because of her command facilities. In 1967 the command ship was the resurrected Escort Cruiser, 10,000 and 30 million pounds, but by 1969 the options were a half-deck ships with 6 Sea Kings and Sea Dart and a full deck ship with 9-12 helicopters. USN experience showed that 6 helicopters was too few leaving the full deck ship as the only option. This was to cost 35 million pounds for 9 helicopters and 36 mil for 12 helicopters in 1968 prices (CVA01 had been cancelled because 70 mill was too much for a strike carrier) and making the hangar big enough for all 12 helos was 37.5 mill but replacing the Sea Dart with Sea Wolf would only save 5 mill.
The command-helicopter ship teams discussed VTOL aircraft but the requirement ]was not justified with reference to it, these were added later and not ordered until 1975;
- 6 years after the GR1 entered service with the RAF.
- 5 years after the decision to end carrier flying was overturned.
- 2 years after the Invincible was laid down.
) but they clearly had an eye for future Harrier operations when these were being talked of in the late 60s and early 1970s.