The SF260 was considered as a Chipmunk replacement for UAS flying back in around 1970. However, political considerations favoured the Scottish Aviation Bulldog - which was the last proper RAF elementary military trainer.
BAC proposed the P-59 single jet, tandem seat jet trainer to replace the Jet Provost - but instead the RAF ended up with the slower, unpressurised turboprop Tucano for basic fast jet training.