On Tue, 19 Jul 2005 18:26:43 +0100, asdf
wrote:

snip
As was demonstrated during the weekend closures for the Wembley Park
works, there is plenty of bi-directional trackwork to the west of
Harrow-on-the-Hill station, and trains can reverse east-to-west in
almost any platform. Platform 2 (the one you describe as 5) has
electric rails solely for this purpose.

ISTR that platform always was electrified but more as a precaution
against the misrouting that occurs from time to time. Unlike e.g.
sending a Marylebone to Rugby train down the Uxbridge line, sending an
electric train down a non-electrified track takes a bit longer to
"undo".