Rupert Candy wrote:

and converting
the electrical system from standard 3rd rail to side-contact.

Bottom contact; side contact was Manchester - Bury, and I think after
conversion, Holcombe Brook, which was originally overhead.

The shoegear in New York is interesting; it's a sort of Manchester -
Bury system turned on its side. It's top contact, but the rail is
protceted except for a narrow gap on the inner side, and the shoe is a
flate plate which comes in from the side to contact the top of the
rail.

Several conventional rail vehicles have been used on the DLR by
contractors, both during construction , and for maintenance.