The Tales of Television Centre (BBC Four, this Thursday)

Yes, that's my understanding too. Same principle as audio mixers.

Also, because of the additive effect, you could quickly end up with large patches of peak white. Modern mixers don't do that, they employ non additive mixes, though today's Sony mixers (probably other contemporary models too ?) have a setting to replicate that effect, Sony call it 'SuperMix'.

I noticed too that they used excerpts from Kenny Everett's B U M sketch (from the 1981 Christmas special, his first outing for the BBC),

If you've seen the sketch you'll know that the end gag is of Terry Wogan opening the door marked "B U M" followed by a loud parp and Terry being blown across the corridor into a wall. I suspect that part of the sketch would have used a set, but the other bits seen in the sketch may have been the actual corridor - if not, then it looked realistic enough.

EDIT: Here is said sketch in full.

I was all water soluble paint, just took a bit of water and it all washed off.

It the days when studios were in use every day for wildly different programmes it was the quickest and cheapest way to change the floor to look like whatever you wanted it to look like.

Joe the Friday producer near the start of the clip is now the overall head of children's.

True - except that CBBC didn't exist in 1974, the branding was only introduced in the 80s. Which means that edition of Blue Peter was not a CBBC programme, even though it is nowadays. Whoever put it onto iPlayer simply saw that it was Blue Peter and applied the CBBC branding, but BBC Four's branding should've been used instead - as I assume is the case for Top of the Pops, which was originally on BBC One.

I think the reason is that it was entered into /programmes (http://www.bbc.co.uk/programmes/b01hz6n0) as an episode of Blue Peter - for that is what it is - and as that programme 'brand' uses the CBBC branding, it is that branding that appears on iPlayer. Similarly, the Top of the Pops episodes use the BBC One branding in /programmes and on iPlayer, even when though they are being repeated on BBC Four.

Yeah, the decision was either to get rid of Yvette or bring in autocue, so they did the latter and Yvette became a better presenter overnight. They had used autocue occasionally before but in the Blue Peter - The Inside Story book, Biddy Baxter says she wasn't keen on it because they used it once for the show to launch the appeal because there were a lot of facts to get across, but it broke down and so the last ten minutes of the show were awful as nobody had bothered to learn the script, so she didn't trust it, or the presenters to put their heart and soul in it if they were just reading it.

In the 50th Anniversary book, Mark Curry says that he was particularly vocal in lobbying for autocue because he said that he started to dread the arrival of the script because he knew he'd have to learn it off by heart, whereas if they had autocue they could look forward to the script arriving because they could actually engage with the subject rather than learn it parrot fashion, with the autocue as a backup, He also says that they got earpieces at the same time so they actually felt like proper presenters in contact with the production team. This is contradicated by Biddy Baxter's book where she says Mark Curry actually didn't want it because he was a proper actor and found it constricting, but while entertaining I'm not sure Biddy's book is all that accurate (most of the quotes "from" presenters are just recycled from the Blue Peter books, written by Biddy).

Sarah Greene says in the 50th anniversary book that one way in which it was easy to learn the scripts for Blue Peter was because Biddy put the same words in her scripts over and over again - "splash of colour" was one - and obviously they were big on recycling stuff as well. I think they might have stopped using autocue again at one point for cost reasons.

I thought it was a great show - some lovely sweeping shots around TVC and lots of archive footage. Top marks too to the production team for respecting the archive stuff, nice mosaic pillars!

Only criticism? So little Saturday morning stuff aside from Noel on Swap Shop. Saturday mornings must have been a buzz in the 80s and early 90s.

I found it interesting to learn that the head of properties (props) had been there for so long.

What will happen to the props and the more production areas. Will they come into more use as part of the studios when they are leased by the BBC and others? Will it become outsourced and run from TVC? Or will it all be retained by the BBC but relocated?

I thought so too.

Fab programme: sentimental, but also relevant to the average TV viewer as well as us 'anoraks'. One to save to DVD!

Out of interest, does anyone know the music used right at the very start? It sounds familiar.

The instrumental portion of "Leyla" from Derek and the Dominos w/ Erik Clapton