Well Easyjet seem to manage OK with quick turnarounds, and it isn't as if the proposition is that different.

I've seen BA do it in 30 mins easily at Gibraltar. Catered at LHR for both flights, pax off by both doors, ex-GIB passengers ready to board at same time, quick clean and away. OK add a few minutes for bigger airports but with the right organisation it can be done for sure.