[lookoutwales]

It was apparently because LWT complained that Thames used to schedule stuff that gave them a poor audience for 7pm. Starting at 5:15 allowed them to start the evening how they wanted. And so instead of the dull stuff Thames put out at 6pm they had The Six o Clock show which was a big hit and set the tone for the weekend.

6oCS was the actual start of the weekend for those of us in London at the time

I wonder if that allegation ever borne out - certainly before the handover was bought forward, Thames were evidently using the Friday 6.30pm slot for shows like Thames Sport (moved to Thursdays after 1982) and Looks Familiar.

Notably, the Six O'Clock Show's success in London seemed to lead to other regions trying similar Friday night formats for a while.

Granada had 'Weekend' for a while with Paul Jones off Manfred Mann, Central News enticed Chris Tarrant back to do Fridays (he later did a stint on 6oCS itself), TSW had 'The Friday Show' with Kenneth MacLeod and I'm pretty sure even Tyne Tees did a similar thing.

Much later on, Border tried turning Lookaround on Fridays into a 'weekend starts here' format - and that was not too long before the merger with Tyne Tees, as well.