During the early 1960s it was becoming increasingly apparent to RAF planners that there was a need for additional radar capability to cover the approaches to the UK. Whilst some coverage was being provided by RN radar picket ships, as well as stations located on various islands, their inability to see over their local horizon left a number of gaps which could be exploited by aircraft penetrating at low level. Whilst some of the gaps could have been plugged using offshore platforms similar to the US 'Texas Towers' these would have been vulnerable to attack, as well as posing considerable construction problems due to the harsh environment found in the seas around Britain.
The RAF were already considering an AEW variant of the Shackleton, replacing the AEW Gannet, but it was felt in some quarters that its ceiling was too low to allow the required radar range, as well as being basically an obsolete design.
After considering several alternative proposals, a version of the Douglas B-66 Destroyer was selected as the basis of the new AEW platform, with an avionics fit based on the AN/APS-96 fitted in the E-2A Hawkeye ( the Hawkeye itself was not chosen as its design was seen as being compromised by its carrier features ).
Italeri EB-66 kit, with rotodome from a Hasegawa E-2