The following currently (1150) appears on the TfL real time website:

The Hammersmith & City Line has no service between Hammersmith H&C Station
and Edgware Road Station in both directions. This will affect journeys from
05:31 on 12/07/04 until further notice.This is due to police request at
Westbourne Park Station.
Message Received: 12/7/2004 5:31:26 AM

Is this true? If so does anyone know what the problem is and, given that
this would seem to be effective from the start of traffic, are there any H&C
trains in service at all, as most are stabled at Hammersmith?