NQY and PLH always worked together on the the LGW route.
Oh no they didn't!!!
NQY, after BN2 days, to LHR, not LGW, was operated by BMA and then Brymon utilising HPR7 aircraft ... now if PLH ever had a long enough runway during the 1980's to accept a loaded HPR7 then you just say the word WOWBOY!
The HPR7 was supposed to be replaced by a DHC7 however a tightening of purse strings resulted in no replacement being available for the HPR7, which had been sold to finance the PLH (1) and ABZ (2) DHC7's that were already in situ, the PLH DHC7 already operating a PLH/LHR/PLH route, thus the NQY route became, supposedly temporarily, piggy backed on to the PLH/LHR/PLH route.
Meanwhile the
LGW route was operated by a DHC6 aircraft, it had nothing to do with NQY, operating PLH/LGW/PLH which then became combined with an EXT/LGW/EXT route once Air UK pulled their Bandit from the EXT route.
Years later BA poached the LHR slots so the PLH/NQY route, which remained combined because the order of a 4th DHC7 became cancelled due lack of finance, moved to LGW but this was many years after the original HPR7 (50 seater) NQY/LHR/NQY route and the subsequently combined route with PLH to/from LHR.