As far as I am aware, they have been allocated to (in order):
Hornsey, Bletchley, Ilford and East Ham. You say where else, so I'll discount Hornsey. in 1986 the 305s/308s/302s were still going strong on the LTS, so I'll discount East Ham. Similarly, the 305s and 309s were still going strong on the Great Eastern and I don't think Ipswich was wired by then, which leaves Bletchley.
The layout doesn't look right for southern WCML, Brum Cross City wasn't wired by then. The layout could fit International, I wan't around then so I don't know how much was developed there. Birmingham International?