Technologist

As other have said both are RedBee white city /Salford and Chiswick / Leeds
But the BBC tightly specified and provided equipment to generate the triggers both for PDC when it was valid and for P/F in running status having the same start at interstitial event before programme, end at end of next interstitial and if the programme is cut on air signal it asap ....
Itv does not have those add on systems relying on what the playout system does,
Also BBC group and Red Bee tend not to have experts who understand linking /tweaking the schedule to give good results ... like they used to have ....
....and as itv and LWT never embraced PDC thus never had.
( remember PDC required c 30 sec clairvoyance )

VTR's

Whilst Play out , obviously, was an important part of a TV station
it really was much the same in the 1950s as it was at the start of the 1990s.....

But then was was the first growth in Multiple channels
and the technology whether its be cart machines the first stills stores and Charecter generators
which started the change in the early 1990s not forgetting computerised scheduling
and then automation (and then linking the two which was why the NTA was late!)
But the pace of change speeded up with Servers and multiple channels
and the video and audio format being Digital - Rec601 and AES3
and the Mixer being just about a card in a PC..... (channel in a box)
and what the people at home got was a compressed version of that!

Unlike in PAL days where what came out of the back of the camera or Microphone was more or less
the same thing as went on the screen at home . almost unprocessed.

So the NTA was a step which soon was overateken -
and the DTA was being overtaken by Servers which loaded
same progresm in the Nations as well - so That Programmes were not off tape
(A bit like in the 70s Telecine masterial was transfered to tape)
SO the move up "the road" was needed for technical operational reasons well as commercial.
and then AS11 DPP came in in 2014 so tape delivery died!
So a lot in those 20 years or so

And now Red Bee spins up extra channels for Chanel 4 in the cloud!
No "on Prem" hardware at all!

And as you can now Code And Mux in the cloud does this mean that play out becomes
ST2110/St2022-6/BT709 live in plus Recorded as AS11DPP or simlar (IMF is better!) file package
and a complete mutiprogramme MPEG TS or IP stream out...

TV Breakdown Appreciation Thread

Picking up a few points
VBI Lines used for subtitles - BBC line 20/333 Itv CH4 5 and most satelite broadcasters line 334 Only
UK tv being BBC Playout used Line20/333 even though there was an Intelfax Anciallary text service on the lines
and not a packet of either service was lost!
The Bond film - Early (disk based) transmission systems sort of scrolled through the subtitle list - and did not blank the output while this was happening .... this could give a similar effect if the time code was not decoded properly - you could see all the subtitles to the end of the progremme in one lump in the worst case or a jump back and then to current time/ Subtitle..... but operationally the subtitles should have been checked before transmission..... -
Porridge subs on the Rugby ...... Despite Subtitles being on lines low in the VBI -this was so that they could be routed with the video and being on a high lien number the Regional/ National Vision mixer would not blank them ... But Ceefax was Bridged from Incoming from London to outgoing to Transmitter - and if the databridge was not set up right -= they bridges subtitles as well!! one thing that I did in the 1990s was t get the same architectures (and thus kit) in every BBC National or Regional site - there were many odd routes etc and even odder and antique kit!
National And Regional subtitling - Only the nation play out programees - so prepared subittles was probably about early 1990s but each nation did their own thing - Live/ Real time subtitles - i seem to remember that Scotland DIY ....
But it was the Mid 1990s That all Nations and Regions - at the same time as we moved to Newfor not ???(cannot remember from Screen ) as the Line protocol
The NTA happened at a time when lots was happening - but it was designed arround manual delivery of the subtitles files on the new EBU3264 spec on 3 inch disk not Propriatory Screen Subtitling systems on 8 in disk.
then had their metadata checked and were logged into the MAM and loaded onto a server which then the playout suite would associate with a particular VT and rehearse. (for Cost and other reasons the TX inserter was on the suite output so key Preview monitors had their own inserters and these output additional info like in and out times and File name !) as the source VT was cut on air the Teletext Subtitle Transmission system TSTS would rapidly download the file to the TX inserter (while the inserter output a Verbose clear down ( 8/0 /888 with clear bit set and then every row of text in the page) so half a seconds worth!) No subtitles would stick!!!
NUDGE - if a programme had a bit cut out for legal reasons - you don't want the subtitles for the cut bit to go out! - IF the edit had been done just be assembly editing everything onto a new tape all was well- there was discontinous time code - so there was both better time code reader (It was VITC not LTC ) and a blanking process so you did not get the "Bond Film" catch up effect ... But if they had got continous time code it did not line up with the file - so the engineers on cue put a great offset ( the duration of the cut out piece) into the time code for all subtiles..... via the nudge panel .- which was more mundanly used when there was a second or two error between the file and the tape . The TX Inseter also did live subtitling
Before the NTA opened the manual Input from 3 in disk was replaced by FTP from Subtitling - this made another key feature easier - Late delivered programmes -
here you would start with say the first five minutes subtitled - and then very four minutes you would get another few minutes from one of Three subtitlers who were working on say 5 minutes with say 30 sec overlap
and it would work with either a growing file or just the 5 minute parts! with a growing file it was easy you just loaded it .... the parts you had to time your reload - a bit like changing Film Reels.
DTA had a different architecture with a PC which was used to load the subtitles from the FTP point (which was monitored by the MAM, to each of the inserter on set of 4 D beta machines so as you loaded the tape you found and loaded the file. There was a nudge avialable on the PC - But the problem was not as pressing as subtitling had higher quality. These inserters output two page 888s the subtitle on line20/333 and the Preview in/ out file name Programme name/ Number on Lines say 10/323 and 11 /324 - it also output Time code in the header so taht inteactive TV Engines could lock to the programme! (Used about once!)
A Preview monitor would see both while the suite output went to a Police unit which blanked the lines 10/323 and 11/324 and More - and put subtitles on lines 19/332 to 21/334(itv) on line 20/333.
The Police unit also checked that there were subtitles incoming - If not alarm and put a Single height top right 888- , if for some reason a programme scheduled for subtitle had not file received it would put out one of four pre programmed Apology subtitles - for a pre programmed time and is no subtitles scheduled a Single height Top right 888- and it did a verbose clear down at the end and start of every item (so clearing any reagsional opt out) and In extremis it could live subtitle - But most live/ realtime subtitling done at source in News and came into the DTA with the video - but a late delivery Programme could be subtitled as it went out
and when the Regional BBC 1 started it also carried the AFD information - as the Video MPEG decoder in the regions did not decode AFD so we used Teletext to do it! - and this was the same box MRG DTP800 used for the prepared File subtitles and Real time /live subtitles in any SDI environment