Unless the plane had autoland I don't think a lot would be gained by a coupled approach.
I would definitely go for that if I were able to set it up. Let the aircraft fly itself all the way to the tarmac, at a speed just above stall speed so that the main wheels touch first. Maybe chop the power 10-20 feet above the runway and let the autopilot and gravity battle it out - my estimate is that the autopilot, in order to maintain the glideslope, would pull up the aircraft a bit, trading speed for a reduction in vertical speed and effectively executing a sort of flare.
Or simply let the A/P fly the ILS but ask ATC to give you a cue when you're 10 feet above the ground. Then disconnect, chop the power, pull back the column until you hear the stall warner, and keep it there until you touch.
Landing on a large airport with a large, unobstructed runway and specialist emergency services nearby would be preferable than landing in a large field of unknown quality, I'd say.
I would have thought it more likely to be a C172 and a talk down by the RAF plane - as in, descend, add a bit of power, left a bit, right a bit. A bit like an SRA. The RAF would have been his "aircraft attitude" eyes.
As I said earlier, it matters greatly whether the pilot could see the horizon, or at least the direction the sunlight is coming from, and thus whether he could keep the plane upright. If he can't, the only instructions you can reasonably give are along the lines of "bank right a bit" "a bit more" "bank left a bit" "pitch down a bit" "reduce power a bit" and so forth. Trouble is, we all do this unconsciously when flying, because we can see a horizon (artificial or real) and now the pilot of the chase plane has to do this consciously all of a sudden (while keeping his own plane in the air simultaneously). No trivial task.
It would be like sitting next to someone in a car and giving driving directions along the lines of "steering wheel to the right a bit more", "break" and so forth. I think James May did that once in Top Gear, having a blind guy drive (race, actually) around the circuit.