[Mike]

there's also no particular historic significance to this event in the way that the analogue switch off had been - and even back then, unless you lived in London, Scotland/Wales or particularly in NI then there was no ceremony to it, no announcement or testcard or anything else. Maybe Arqiva were generous enough to shutdown once the current programme had ended, but not necessarily.

They did announce that DSO was taking place in the regions other than the ones mentioned though:
www.youtube.com 

But it wasn't pomp or ceremony, the symbol with an announcement and then some way through the late film it cut off air.

Unconnected to this thread, but there's a linked clip of C4 Analogue coming off air from Sutton Coldfield there, and just before it does there's a jump - is this the transmitter going to RBS mode before finally being switched off a second later?