UK Wartime Broadcasting Service - WTBS

Normal radio and television broadcast services would be replaced by a special war time radio broadcasting service operated by the British Broadcasting Corporation (BBC). A single national service would commence during the transition to war period, changing to a regional service in the post-attack period.

Outline of the WTBS

The BBC referred to WTBS as 'Deferred Facility" or 'DF' internally and should not be confused with the abbreviation for {radio} Direction Finding.
The plans for the WTBS changed during the cold war period to match changes in the Regional Government plans, technical reasons and the listener base moving from Medium Wave to VHF Stereo stations. The original plan was for a single countrywide channel on Medium Wave, using low power transmitters installed during WWII.
There was little in the way of fallout protection or standby power in the seventies. In the eighties, plans were developed to provide fallout protected accommodation for staff at Moorside Edge, Stagshaw, Burghead, Black Hill, Start Point, Brookmans Park, Washford, Sutton Coldfield and Wenvoe. With standby generators required to maintain the WTBS in the very likely event of the normal electricity supply being disrupted at Black Hill, Droitwich and Start Point. To refurbish the existing protected accommodation at Droitwich, Wrotham, Westerglen, Lisnagarvey, Holme Moss, Oxford, North Hessary Tor, Daventry and Clevedon. The WTBS studios at Wood Norton would be refurbished with an EMP screen, improved air conditioning and replacement diesel generators. A new standby WTBS studio at an undisclosed location by 1988-1989.
The WTBS national programme would be sourced from an underground bunker at the BBC Training School, Wood Norton on the A44, 2.5 miles north-west of Evesham, Worcestershire. Regional Government Headquarters (RGHQ) were equipped with a basic studio allowing regions to break out from the national programme source and give information pertinent to their local area.

Transmission Timescale

The now declassified 'Secret' BBC War Book (1974 edition) gives an insight into the programming policy and timescale for the introduction of the War Time Broadcasting Service (WTBS). The decision to invoke the WTBS is a purely government function taken during the Transition To War (TTW) period. Many parallel activities would be taking place in the TTW period, such as manning up the UKWMO and ROC.
The BBC War Book describes how the BBC would maintain its independence at first, while keeping the WTBS preparation covert: During a period of tension BBC output would be expected to reflect the international situation, and modifications would obviously be made to the advertised programmes, in order to report and comment on the crisis as it developed. How this could best be done would rest with the BBC to decide in relation to circumstances prevailing at the time. . . . another section of the book includes Until authorised to do so, the BBC must not take any action of a character which might alarm the public.
Timing of the warning to the BBC to switch to WTBS is set out in the Government War Book. The BBC War Book does warn that if events were to move swiftly, the timescale may be less, nevertheless it would take them three hours. The Government War Book stipulates that the BBC requires 48 hours' notice to prepare for the WTBS, and a further 2 to 4 hours' notice when authority is given to start it. Having taken these timings into consideration, and without consulting the BBC, the Government will decide the actual time of its start and the BBC must be prepared to act accordingly. The start of the WTBS is known as the 'N' hour and set by the government.
Timing of the Introduction of the WTBS
timing chart
The start time for the WTBS is called the 'N' hour ('N' for National). Sixty minutes before this, the 'A' hour marks the start of a 30 minute 'A' period ('A' for Announcements). All of the BBC radio channels on medium wave and VHF combine and transmit announcements informing listeners in which Civil Defence Region they belong and the appropriate tuning frequencies on Medium Wave and VHF.
The 'S' hour marks the start 30 minute 'S' period ('S' for silence) leading up to the 'N' hour, when the WTBS begins. In order to avoid the complete cessation on all wavelengths during the 'S' period, Droitwich long wave with its countrywide coverage will transmit the same announcements as on Medium Wave and VHF, and repeated for the whole 60 minute duration of the 'A' and 'S' periods. The 'S' period allows Medium Wave transmitters to be retuned to their WTBS frequencies and both VHF and Medium Wave program feeds to be rearranged.
At 'A' hour the BBC and ITA television networks will be combined for sixty minutes before closing down at 'N' hour. During this period they will transmit a specially recorded programme, originated by the BBC, describing the impending WTBS. Television broadcasts are not within the remit of Regional Government controllers and would only restart when permitted by Central Government.

Early Stages - Group 7 Transmitters in 1953

In WWII multiple low power transmitters, known as Group H, all transmitting the same programme on 1474 kHz were used to prevent the Luftwaffe from being able to use the BBC high power transmitters to guide their bombing raids.
The Group 'H' sites were adapted or new sites built nearby served in the early stages of the WTBS to provide a regional service. At that time, Regional Government was based in a Regional War Room, the concept of Sub-Regional Controls (SRC) and Regional Government Headquarters (RGHQ) came later.
1953 Group 7 Transmitters
Transmitter Sites
I don't currently have any information on how the programmes were distributed over the GPO network, but the diagram shows the transmitter locations and regional frequencies. Normal peacetime telephone circuits between exchanges that were only switched through to become Private Circuits when they were needed, known as Emergency Circuits (ECs) were common at this time, and were very likely the means of connecting the WTBS transmitters to their Regional War Room.

Phase 1 Distribution Network

The 1976 diagram below shows the programme distribution network. The lines linking sites represent one or more circuits carried over GPO/BT private wires, BBC's own microwave network and in some cases direct reception off-air from another transmitter. Some circuits, such as those from the RGHQs are exclusively used for WTBS, but those linking transmitter sites may have a peacetime purpose too.
1976 Network Diagram (Phase 1)
Network Diagram
Circuits carrying programmes, known as 'Music Circuits' have a much wider bandwidth than normal telephone speech circuits. They are accompanied by a speech circuit 'Control Line' to allow liaison between the two ends for technical and programme continuity purposes. Under WTBS conditions, these could be pressed into service to carry the broadcasts if the music circuit failed but with reduced sound quality. Documents in the National Archives, suggest as a very last resort Trunk Subs to the GPO Emergency Manual Switching System EMSS from BBC premises could be pressed into service to feed WTBS announcements or relay the message to be announced by someone in the transmitter site's protected accommodation.

A BBC Engineers Viewpoint on WTBS

A retired BBC engineer, shared some of his experiences, edited into the paragraph below.
. . . In the 1970s and 1980s the wartime priority for the BBC would have been local radio services on medium wave. These would keep going as long as possible. All the local radio medium wave transmitters had standby generators. All the local radio studios had standby generators. (I visited Radio Sheffield in 1982 and they had a generator. I don't think they had a fallout shelter.) Circuits between the studios and transmitters were sometimes duplicated, or backed up with "RBR" - Re-Broadcast Reserve. That is, if the incoming circuit from the studio failed, the transmitter would automatically rebroadcast a signal from another transmitter. In the case of BBC local radio medium wave services, this was the VHF FM service from the same local radio station. . .
In Phase 1, Holme Moss received its WTBS programme from Moorside Edge, but became an important centre under Phase 2 plans. In the 1980s, BBC Holme Moss transmitted BBC Radio 2, 3, 4 VHF FM services to around 10 million people. BBC Moorside Edge transmitted BBC Radio 1, 2, 3, on medium wave to a similar number.

Both these stations had standby generators. The diesel engines at Holme Moss were tested every Wednesday morning. I recall that the whole station was run on diesels for a couple of hours, just to make sure everything worked.
There was a small shelter in the basement at Holme Moss. From the age of the equipment, I guess this was installed in the late 1970s. There were about 10 bunkbeds and 2 incinerating toilets.

There was one 19 inch equipment rack. I remember an audio mixer and a simple patch panel with all the incoming circuits, including those designated as DF, and patch circuits to the transmitters upstairs on the ground floor. The microphone was locked away in a cupboard, just in case anyone might be tempted with an impromptu DJ session on air. I also recall a control panel to switch the main transmitters on and off, and to start and stop the diesel generators. There was no tape recorder and no "secret" tapes.

The shelter was quite basic. There were no airtight doors or air filtering systems. It really amounted to a cellar with some bunk beds and a radio equipment rack. The shelter was never used as part of the day to day station operation.
All of the ordinary station telephones were normal lines on the local British Telecom exchange. . . . . . . . . Holme Moss also had a number of other lines on the BBC EMX - Engineering Manual Exchange. This was a separate switchboard at Holme Moss with direct connections to the control rooms at BBC Manchester, BBC Leeds, BBC Newcastle and the BBC transmitter at Pontop Pike. I recall that the telephone line from BBC Newcastle was a "deferred facility" and could have been used to broadcast programmes if all else had failed. That is, the BBC could have relayed programmes from the North of England, instead of the South of England, if required.
We also had a direct line in the control room to the civil defence headquarters in Preston. This phone was never in day to day to use, but I do vaguely recall an annual test when we were called and required to answer with a given a code word. This phone was accidentally knocked off the hook many times, but whoever was at the other end never called to complain. On a couple of occasions I pressed the "Call" button but nobody ever answered. So whatever exchange this line was connected to, it must only have been used if the various control rooms had been staffed in the direst emergency. This line was only telephone quality, but it could have been connected up to the transmitters as a last resort. This circuit is not shown on any diagram as it is not a programme circuit, but UKWMO Sector HQ at Goosnargh near Preston was the reserve centre for issuing the Attack Warning, via HANDEL. Preston had a direct line to Flylingdales BMEWS facility. Clearly the engineer did not know where the Preston centre was or its purpose.
As a further backup Holme Moss was equipped with RBR - Re-broadcast Reserve radio receivers from other BBC transmitters. Holme Moss could receive VHF FM programmes off-air from Sutton Coldfield to the south and Pontop Pike to the north. Similar receivers were installed at transmitter stations throughout the country. The "fallback towards the south" arrangement was completely automatic. If the entire BBC microwave or BT circuit network failed, all Radios 2, 3, 4 VHF FM stations would rebroadcast programmes from the next station south.
Recalling this about Wood Norton. As a BBC engineering trainee I spent almost a year at Wood Norton. Some of the rooms in the Bredon Wing bunker were used as classrooms. I  remember having lectures in windowless rooms a couple of floors underground. I never went into the control rooms, but they did exist. The diesel generator air intakes were on the side of the Bredon Wing building. There was a microwave antenna mast on top of a nearby hill with, I think, a standby link for wartime use to the BBC transmitter at Daventry. The chap has a good memory as this link is shown on the phase 1 diagram, until it was removed in the mid-eighties, there was another microwave link between Wood Norton and Drakelow RGHQ 9.2 and continuing on to at tower on Brown Clee Hill. Maybe this removal coincided with WTBS Phase 2 implementation.