(27 Feb 2014, 4:20 pm)Dan wrote Had wondered that myself, and I've asked around and nobody I know has known either.
Remember, evenings throw up the opportunity for them to appear on 3s too.
Was wrong with this one - been so long since I've referred to timetables. The 20s run off 3s, so all evening 20s from 1800 onwards are allocated ALX300s.