On the 31st January 1973 a group of students from Imperial College London visited the transmitter sites of the IBA. The students were all members of STOIC, the Student TV service from the college. At that time London still had the original 405 line black and white TV service as well as the relatively new (1969) colour 625 line service. Croydon was the 405 line transmitter and Crystal Palace was the 625 line transmitter, both of which were toured. You will hear some 'vision buzz' on audio.
This video is audio only.

00:00 Start at Croydon building with Intro
10:10 How are the transmitters cooled?
10:53 These transmitters are VHF 405 lines
13:00 Colour arrives late 1969
17:10 UHF doesn't travel well, but VHF goes further
18:34 Croydon monitors and runs Crystal Palace UHF
19:34 Sharing sites with the BBC
25:25 Combining unit
25:50 Switching to reserve transmitter
28:10 Master Oscillators
30:09 On-site BBC design standards converters 625 to 405
31:24 D.I.C.E (IBA design)
33:00 Live programme contractor (Thames TV) fault on air
39:11 Move to Crystal Palace transmitter building
40:42 Mention of the Crystal Palace building history
42:12 The Crystal Palace was burnt down 1936
43:12 UHF transmitter built by Marconi (in-service 15 November 1969)
49:25 The Collector at 70oC is Vapour Cooled
54:10 End and lock up of station