When the RAF has hundreds of Hunters able to be converted into the FGA role, hundreds of Canberra for the light bomber role and a hundred or more V bombers for the medium bomber role there is no need for a versatile lightweight fighter-bomber.
In the mid-late 50s Britain was a quasi superpower who didn't have a requirement for multirole aircraft as much as other powers. She was still in the market for top notch single role aircraft much like the USA and USSR, and if these aircraft (F101, F104, F106, Su15, Mig 21) aren't as adaptable as other aircraft then who cares, they have fleets of other, more appropriate aircraft for those roles.
In the mid-late 50s Britain was a quasi superpower who didn't have a requirement for multirole aircraft as much as other powers. She was still in the market for top notch single role aircraft much like the USA and USSR, and if these aircraft (F101, F104, F106, Su15, Mig 21) aren't as adaptable as other aircraft then who cares, they have fleets of other, more appropriate aircraft for those roles.