One thing which is quite odd when thinking about it is now the franchises changed over at Midnight.
So you either had the outgoing franchise being a bit miserable heading up to midnight, or the new franchise talking about how great regional news will be at just past midnight. Loads of staff had to be working at both franchises, plus people flicking the switches, amongst all this the viewers were just wanting to celebrate new year and not really that interested in how there would now be sub opts and more newsrooms across the region.
The TV day starts at 6am in every other circumstance so maybe the franchises could have changed at that time as well, with the new ones launching at 9:25am
I suspect because by that point ITV at least was 24hrs, midnight seemed as good a time as any to handover. A new year starts at midnight so the new licences can start at midnight too. I suppose there was nothing technically to prevent a changeover at 9:25am on Jan 1st 1993, though that would have effectively made GMTV the first of the new broadcasters on the air at 6am and any farewell packages such as the one Thames made would have effectively gone out at, like five to six in the morning when less people would have noticed they were going.
I dare say the switches from franchise to franchise were automated; no different really to the handovers that had been happening every morning at 6am and 9:25am for the previous nine and a half years. Virtually invisible at the time, on full view now thanks to VHS and YouTube