What is surprising is how much the BBC Regions used to contribute to network programming. Not just the network production centres, but Leeds, Plymouth, Norwich, Newcastle all used to have their stuff shown on the network. Some of these were in strands that repeated regional documentaries but it looks like the regions all got regular network commissions too.
They were a bit more flexible in those days and I don't think it was a specific drive to commision stuff from the regions, with specific quotas, but just that someone in the regions had an idea and they just pitched it to the network. The regions in those days would have a much wider range of production staff because they would have the regular regional shows on BBC1 which could be anything, so you'd get something like Gardeners Direct Line on BBC Leeds getting a big audience and moving lock, stock and barrel to the network. Same with Keith Floyd, David Pritchard at BBC Plymouth spotted him and put him on locally and he stayed with him when he moved to the network, and his desk was at BBC Plymouth.
In many ways these weren't really regional productions but just a quirk of where the production team were based. In one of the BBC Handbooks they talk about how BBC Pebble Mill used to make a regular contribution to Match of the Day but that seems to be entirely because one of their directors John McGonagle used to be based in Pebble Mill and whenever they did a match from the Midlands he'd do it with a Pebble Mill crew. The Handbook reports that he'd now retired so Pebble Mill's contribution to Match of the Day had now ended. Similarly Mike Craig used to be one of the Beeb's radio comedy producers and worked out of Manchester, and when he retired he wasn't replaced and that was the end of radio comedy from Manchester.
I don't suppose it's too different to what we get today because if a TV producer now found the new Keith Floyd in Plymouth they could still make the show from Plymouth, but now as an independent producer. Indeed you could probably see the regions in those days as the equivalent of today's indies.