Several references to lapsed licences. If this is the case,its a question of re-issue by CAA (requires current medical and at least one current class/type rating)
More often pilots who are "lapsed" mean that their SEP(L) is lapsed. In this case some kind of re-training is required before the LST with an FE. I would not normally expect to send somebody to fly solo (on my licence) in this case. Get them up to standard, pass the test and fly on their own licence.
It is a little disappointing to hear instructors who should know better, talking about lapsed PPLs, unless that really is the case. Remember a UK PPL (ie pre-JAR) is issued for life.