Good Morning Britain - the launch

I wasn't aware GMB had been deemed a failure?!

Although there was an ad break which finished at 9:24:59 so that there wasn't a harsh jump at 9:25:00. The routing of the picture from studio to the transmitters was different after 9:25 also, although most viewers wouldn't have noticed any of this.

Back in the mid-late nineties UTV was the only region not to provide regional GMTV news. It was instead produced by other companies, including Reuters. The switching meant that UTV's ancillary 600 teletext service wasn't carried for some time during GMTV's hours. Instead, LWT Plus was broadcast in Northern Ireland, even during the week!

Programmes bridging 'franchise' crossing points are not new. There'd often be something that straddled
the 19:00 (later 17:15) Thames/LWT Friday switchover, if Christmas Day etc fell on a Friday. Complete with
a lovely splat at bang on the switchover time, and didn't TV-am stay on air until 10:00hrs on the morning of the Manchester airport tragedy in 1985 ?

No - this is where the ITV operation confuses people. STV and UTV, along with all the other regional ITV licenses (aka franchises) don't have the right to broadcast between 0600 and 0925. Instead the Breakfast franchise (licence?) holder does. There is a switch in responsibility and transmitter access every day - which means that ITV Breakfast (formerly GMTV) broadcasts between 0600 and 0925 across the UK. So Good Morning Britain is not broadcast by UTV or STV, instead it is broadcast by ITV Breakfast in the STV and UTV regions. STV, UTV and the ITV regional franchises only have the rights to broadcast from 0925-0600 on ITV. (It gets more complex when it comes to ITV2-4, CITV etc.)

This may seem to be "Angels dancing on pinhead" territory, but it is significant as it means STV and UTV get no advertising revenue from the output during GMB, and have no rights to the programmes to put on their catch-up services. ITV Breakfast wouldn't want a third-party catch up service hosting their output and making money from advertising without an agreement being in place. I guess they have an agreement with UTV but not STV?

In the early days of the breakfast franchise you'd see the transmitters physically switch between TV-am's feed and the local franchise feed at 0925, with a lovely crash, bang and frame-roll...

The ratings would suggest that it is, and within the industry it is being regarded as one.

On the subject of the STV/UTV/ITV Breakfast franchise arrangements, I remember seeing STV HD a few years ago showing a 'This programme is not available on STV HD' caption during Daybreak, presumably as they had either no right or compulsion to show it. Is this still the case, and is it (or has it ever been) the same on UTV HD?

That was true, although iirc it was only on DSAT. I think there wasn't STV HD on Freeview then.

In the London area of the UK there would have been no re-routing of the studio/service provision because Carlton/LWT/GMTV all came from the same presentation area on the SouthBank.

Lest we forget the famous incident (in 1994?) where UTV took themselves on air during GMTV's broadcasting hours to cover a particularly important story to the people of Northern Ireland.

I recall in the early 90's some Australian soap starting off at around 5pm on Thames and being switched out at 5.15pm via LWT. 'Postie's' line switches were never synchronous so there was no point in trying to mitigate against the inevitable 'splat', although some would try to perform a frame lock to try and minimise it.

This is true, LNN's facility as it was, though there was still feed switching at 06:00hrs and back again at 09:25, because GMTV had macro regional advertising, (that LNN handled). The outgoing feeds to the regions were reconfigured for GMTV's timeslot. Because the feeds were more or less synchronous, and were
also done in the SDI domain, not really a splat, more of a green glitch and click (sometimes).
In 1999ish I had to relocate the custom made gizzmo boxes (one main, the other standby) from one bay to another. That was a laugh !

Was there not a GMTV ancillary teletext service at some stage, at least in UTV-land?