In 1972 the UK government prepared a list of 106 “probable nuclear targets in the United Kingdom”. The list included 38 towns, cities and centres of government, 37 air bases [US and UK], 25 control, communications and radar facilities and six naval sites.
The list assumes the Soviets would attack 24 British cities [with no military value], and 14 centres of government [some of which were in or near cities]. For example, Edinburgh and York are targets because they are ‘centres of government’. Both had bunkers which were intended to be Regional Seats of Government. The Edinburgh bunker was in Barton Quarry. There are also some cities which were targets because they had naval bases [e.g. Plymouth and Portsmouth]
The military warned that the list might not include all possible targets since the Soviet Union could launch a nuclear strike against Britain with 150 land-based missiles, plus an unknown number of submarine-launched missiles.
Some of the assumptions in the list were questioned. Home Office scientific advisers “find it difficult to see why an enemy would wish to deliver a three-megaton attack on Swansea and on Leicester when, in their view, one megaton on each target would be sufficient to cause almost complete destruction of those cities.”
That seems right. Swansea has a population of 200-300,00, depending on how you define its boundaries. It is not a big place. I used Alex Wellerstein’s NUKEMAP to model a 3 megaton attack on Swansea. The blast would have flattened a good part of South Wales and caused 3rd degree burns out to 20 km.
It is also not clear why the Soviets would wish to annihilate Huddersfield and Kidderminster.
I suspect the military were overly pessimistic about Soviet intentions, perhaps to create an equivalency with the UK’s plan to attack 48 Soviet cities [under the US/UK Single Integrated Operational Plan [SIOP] for a nuclear attack on the Soviet Union the RAF had been assigned the task of destroying 48 Russian cities] , perhaps with a view to the size of future military budgets.
The plan also assumed that the RAF radar station on the tiny Scottish island of Saxa Vord would be hit with a 3 megaton bomb. The result is shown below. A bomb of that size would not only destroy the radar station but also sterilise the entire island. A more likely scenario would have seen the base attacked by conventional weapons.
Guardian article on the map. link
A more realistic map
For a more realistic map of likely UK targets see the Square Leg Exercise map in this post. It will also let you see what the UK Government had planned for you pre and post attack.