Unless the plane had autoland I don't think a lot would be gained by a coupled approach. 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. I don't know where he landed but a big grass airfield would have been useful.
Poor guy though, reports say he is seriously ill. Presumably from an unknown medical condition (as in, unknown when he started the flight).