On Mon, 21 Jul 2008 20:42 +0100 (BST), Colin Rosenstiel wrote:

Nowadays, the Barking sidings are mainly used for C stock, with the
odd bit of D stock, but I think before the Jubilee extension and its
effects on Neasden, there wasn't much C stock stabled at Barking, but
some was stabled at Neasden. I wondered how they went into service
from there, but I never saw it happening.

Via the Met and Baker St, surely?

But did they go into service at Wembley Park (or Finchley Road, or the
Met platforms at Baker Street), and if so were they advertised as
Aldgate or Circle Line?