Why ITV is pulling out all the plugs 

24 June 2019 tbs.pm/68755

From the Sunday Times for 17 August 1969


SUNDAY, September 7, is S-night — the culmination of the biggest television switchover ever mounted. At 11 p.m., teams of well-drilled engineers will descend on the studios of the independent television companies and pull out the plugs on sets of specialised electronics equipment. Then they will load the delicate racks — worth £380,000 [£6.5million in 2019 allowing for inflation] a set — on to lorries and drive carefully through the night to TV masts all over the country. There, the equipment must be unloaded, re-connected, tested and checked-out ready for broadcasting to restart at 4 p.m. on the Monday.

Although the public will not see the results until November 15 — when ITV and BBC 1 colour and 625-line broadcasts will begin — these 17 hours will be the climax of a multi-million pound operation. The Independent Television Authority — the ITV governing body — is spending £10.5 million [£180m] to duplicate the present 405-line transmissions with a 625-line colour service — the TV companies will have spent around £20 million [£341m] on re-equipment by the time the conversion is complete — and the BBC is spending millions more to put colour on BBC 1.



As the chart shows, the ITV studios are already producing programmes on 625-line standards but at present the signal is converted to 405 lines before being fed into the distribution network It is the electronic convertors to do this job which will be transported to the transmitters on S-night.

After S-night, ITV programmes will be networked round the country as 625-line pictures and only converted to 405 lines at the transmitters. And after November 15, there will be two sets of transmitters operating — one sending out 405 line pictures as at present, the other providing colour, or black and white, on 625 lines.



No one has ever had to carry out a nation-wide switch of TV line standards before, and unless France decides to get rid of its 819-line service no one is likely to do so again in the foreseeable future. For the ITA it is an operation requiring knife edge timing — it is simpler for the BBC because all its network links pass through a single switching centre in London.

S — for switch — night was originally supposed to be July 7, but ITV’s labour troubles put it back two months. “We’re very tight on dates now,” admits Howard Steele, the ITA’s chief engineer, “but no one has advised us they’re not going to be ready.”



One company with a particularly tight conversion schedule has been London Weekend Television. The company was not able to move into its Wembley studios until May 1968 and the conversion to colour and 625 lines could not begin until September, leaving only 14 months in which to complete it.

According to Reg Swain, LWT’s head of planning and installations, this has only been possible through really thorough critical path analysis, using a typewriter terminal hooked in to Time Sharing’s dial-a-computer service. This has been used to co-ordinate the eight different facets of the £2 million [£34m] conversion programme, each with its own critical path schedules. “My own estimate is that it would take something like two years to do the job manually,” says Swain, “but we haven’t slipped one item — except one delivery which is going to be a month late.”



But the margin for error is still perilously small — especially on S-night. The biggest hazard is that one of the lorries could have an accident with its precious cargo putting one of the ITV regions off the air for a while. Steele’s engineers did consider more leisurely, less risky ways of making the changeover but they would not fit within the ITA’s tight budget.

As an extra precaution the ITA will have two sets of spare convertors standing by on lorries, and those at transmitters in particularly remote places or which have to be taken on a sea crossing will already have been installed. But Steele admits there is still an element of risk in the operation.



And there are literally thousands of things which could go wrong and delay the November 15 starting date in some areas. In particular there is a 50-50 chance that the Emley Moor transmitter in Yorkshire — the one which was blown down in the icy conditions last March — will be a few weeks late in beginning 625-line transmissions, as much because of paperwork delays as anything else.


Kif Bowden-Smith writes:

The conversion to UHF and colour was slow going for many reasons. Originally, BBC-1 and ITV were to have launched on 625 in black and white in 1968, going colour in early 1969. But Pye and Marconi, who manufactured the transmitters, couldn’t keep up with demand. Additionally, economic woes caused the government to restrict capital expenditure by the state-owned industries, which included the BBC and the Independent Television Authority. Thus there was no money to pay for the transmitters that Pye and Marconi couldn’t provide.

When added to the much poorer coverage that UHF had compared to VHF – see the red lines on the Yorkshire map and compare them with Emley Moor’s UHF coverage in green and the hefty number of booster transmitters arranged around it – and the reluctance of people to buy or rent expensive 625 sets for a palpably worse picture in many cases, it’s no wonder that it took until 1985 to switch off the 405/VHF system.

You Say

2 responses to this article

Alan Keeling 24 June 2019 at 8:38 pm

As you could see in the illustrations, the coming of colour on BBC1 and ITV meant that Test Card D ceased to be broadcast, to be replaced by Test Card F seen in monochrome. The start of colour on ITV also meant that the old, slightly dated “Picasso” ITA Tuning Signal was replaced by a three colour non adjustable ITA start of day caption.

Steve Gray 3 July 2019 at 3:00 pm

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