PPrune Radar,
1. Even partially configured at the top of an ILS, a 737 will still be doing 3nm/min. Small windscreens and high workload = difficulty in aquiring visually, light traffic.
2. When fully configured, a 737 is not very manouverable, and in fact, any requirement to deviate off a stable approach would almost certainly require a go-around. Any TCAS RA when fully configured does require an immediate go-around. There goes a tonne of fuel, now even higher workload, still with the conflicting traffic in the area.
I would suggest that airmanship would dictate that a light aircraft approaching a jet on approach to an airfield, from whichever direction, should give it some room. You will be able to see us well before we can see you.
Also TCAS is only able to provide us with a traffic RESOLUTION, if both aircraft are using mode C.
Even in the circuit at Sandtoft, Mode C helps the aircraft and radar.
Plenty of space out there, we just need to learn to share it.