1989-90 What if?

Not quite.
The full 'money in the envelope' bids of all the prospective consortiums were annouced by the ITC on the day itself.
Those figures have been public knowledge from day 1.

By the way FOI requests are not quite the 'magic keys to the play room' people think they are. There are still all sorts of get outs, and disqualifications from making public some information if it's deemed sensitve - either personal or commercial.

I've always wondered why the London weekday and weekend franchises were never merged together. Always seemed like a strange anomaly that didn't get corrected.

I think the discussion was such that the IBA wasn't prepared to face one massive broadcaster being a loser, which inevitably that would have engineered. Best to keep both on side during the bidding process.

Last I checked that it still sticks to this day, in that the ITV London Weather sponsorship still has the weekday/weekend split.

It was weird considering it was known the regulator wanted 2 stations but only one news service for the region. And that didn't happen until 1993.

That's because the main reason for the split was ad revenue, not plurality

Not entirely the case for news, from 1982 Thames provided LWT's news, directly as a 15 min insert into the 6 o clock show, and scripted for LWT's CAs to read at other times. It was later in the 80s that LWT broke away with an LBC provided agency service. As you say come 1993 and Carlton replacing Thames, LNN was jointly formed for news, (and playout)

How did that actually work in practice once LWT started their own news service? Was there a reciprocal agreement to share footage or would both stations' teams be out covering big stories?

I'm thinking of some kind of incident that happened at the weekend which LWT might get footage of which results in a mid week court appearance that Thames cover, would LWT provide library shots for the package?

LWT's news provision was provided by Screen News and subsequently by Chrysalis in the late 80's.

I don't recall the 1980s LWT bulletins to be much more than a CA read and static photographs?

Wasn't the feeling also that one London ITV company would have been too dominant?

... up until the news service was provided by Screen News and then Chrysalis in the late 80's.

Yes, that seems to be readily agreed within the industry.