On 5th Oct 1997, whilst BBC2 was broadcasting the above, BBC1 was showing this slightly modified Test Card G. It was accompanied by the standard BBC1 stereo tones. For both of these, sound was in NICAM but there was no teletext or PDC signals. BBC1 and BBC2 both switched over to these images at the same time, and reverted back to Test Card F at the same time. It is thought they were broadcast only from Crystal Palace, unless of course you spotted them elsewhere? They were broadcast as part of a switching test by the BBC. If there were ever a major incident at Television Centre, London, BBC Network Television would evacuate to Pebble Mill, Birmingham. A switch would be thrown so that Birmingham were in control of the network, where they would then attempt to run as normal a service as possible. These two test cards were transmitted from Birmingham, in order to test that the switching facility worked.