I think it's the abandoned Epping-Ongar section, near Epping: I think you
can
see the loco under tarpaulin from a nearby overbridge.

Can you give any more details - I missed the prog ?
Cheerz,
Baz

The loco is (I think) L11: it's 2 ends of driving cars from Tube Stock (of the
sort which was, or possibly still, on display in the Science Museum, South
Kensington) welded together to form an electric loco for LT. It's
yellow-coloured - I am sure you can find a picture of it in old LT stocklist
books (Ian Allan) etc.

Marc.