I've toyed with such a post myself years ago. But I'm torn between it being Alternative History and Theoretical.....
P1125 gets closest but having been burnt over P1121, there was zero chance of company funding. Though with reuse of P1121 parts and twin Avons it's almost ideal.
Brough did turn out later designs that effectively are a STOL backup for the P1127 and the NGTA. But the latter wouldn't be ready until too late. Though the former......using well understood blow, high wing, single Spey......scale it up to a Medway and this would match the P1154 performance.
Now if they'd come up with this earlier, and they could have.....say a STOL backup for the P1154......
If HSA board had run the design in parallel with the P1154, they could have offered to switch. Being cheaper to produce and run....
Just near the end in '57 Saro did ask for last minute submissions to F155 stating that relaxing requirements could allow them to design a twin engined or single large engined aircraft for the RAF.
And Folland for all their smallness turned out quite nice concept in the Gnat mkV and the VG trainer/fighter.
There's more but I'm out of time at the moment.
