I definitely remember a Transmitter Information caption appearing during one of the long intervals around about 1989 - just white writing on a blue background. If I remember, the transmitter was in the TVS region and as I was watching in Central Scotland I can only assume the caption was being broadcast by Channel 4 in Charlotte Street.
And on the other subject....
Channel 4 never broadcast regional opts as such - although, of course, advertising was sold and transmitted by the ITV companies until the end of 1992. However ITV Schools from 87 to 92 was - in effect - "ITV on Channel 4" so STV, Grampian and Ulster often opted out for their own schools programmes.
I think there may have been one occasion during the 1987 election when Channel 4 had to screen an SNP Party Election Broadcast late at night. I vaguely recall a discussion about it on Right to Reply. Presumably, electoral law meant the broadcast had to be shown in Scotland. The debate, I think, was about why it was shown late at night rather than in the usual slot after Channel 4 News. C4's explanation appeared to imply that it was to make sure it was only seen in Scotland. It may well have been the case that STV and Grampian opted as Channel 4 was closing...
On another occasion, late in 1985, STV had the rights to a live Scotland World Cup Qualifier but were unable to show it themselves... partly because of TV-am and partly because of Schools. So Channel 4 screened it on their behalf - as far as I know across the network. I was off school that morning and well remember watching! Incidentally, it's the only time I ever remember seeing C4 closing down with the clock during the day and going to the test card BBC style...
On another occasion, late in 1985, STV had the rights to a live Scotland World Cup Qualifier but were unable to show it themselves... partly because of TV-am and partly because of Schools. So Channel 4 screened it on their behalf - as far as I know across the network. I was off school that morning and well remember watching! Incidentally, it's the only time I ever remember seeing C4 closing down with the clock during the day and going to the test card BBC style...
There is a file on the MHP PP to back your claim up, Scotland played against Australia, but it was a 7am kick off (or so), but it definately was Networked on C4, whilst TV-am was on ITV.