Declassified documents revealed the 38 towns and cities which UK officials believed would be the prime targets for Russia.
And this was alongside another 70 targets of military bases, communication centres, airfields and other pieces of key infrastructure believed to be at risk during the Cold War.
Death tolls predictions reveal the attack like this today would kill instantly killed 7.7 million Brits in the towns and cities alone, based on the size of nuclear weapons in Vladimir Putin’s arsenal.
Revelations come as Britain and Russia’s relationship remains on a knife-edge following the attempted murder of MI6 double agent Sergei Skripal.
Putin’s officials have already warned do not threaten a “nuclear power” in a chilling shot across the bows of the UK.
Daily Star Online can now reveal the horrifying consequences of what would happen on day one of war between Britain and Russia.
London would be hit the hardest in a bid to wipe out the heart of the UK, totally vaporising the city within 1.5 square miles and instantly killing 950,000 people.
Then within 84 square miles the blast would be felt through Greater London, collapsing buildings and causing widespread damage.
While in another 6.9 radius from the blast, which would affect an area of 148 square miles the surrounding the city people as far as Crystal Palace and Brent Cross would suffer third degree burns.
In total 2.3 million people would be injured in the strike on London alone - and that was just one of the 38 towns the UK Government believed Russia would strike.
Birmingham, Manchester, Glasgow and Liverpool would be the the next hardest hit when the nukes came down.
Death tolls of 420,000, 371,000, 325,000 and 300,000 respectively would hit these key cities and render large parts of them uninhabitable.
Casualties then range from 270,000 in cities like Bristol, right down to just 7,500 in places such as Salcombe.
But the total death toll for all 38 towns and cities revealed by the UK was the horrifying 7.7 million.
These simulations are based on nuclear historian Alex Wellerstein’s NukeMap tool which predicts blast radiuses and casualty counts to show the horror of nuclear weapons.
Nuke strikes were simulated using one of Russia’s most common nuclear ICBMs the Topol SS-26 - known to NATO as the Sickle - of which Putin is believed to have around 160 in service.
And these weapons carry nuclear warheads with the explosive power of up to 800,000 tons of TNT.
That is more than 46 times more powerful than the bombs the US dropped on Hiroshima.
Britain compiled it what it believes are “probable nuclear targets” in a secret plan signed off by prime minister Edward Heath.
It noted these were not the only targets they believed the Soviet Union would strike, but simply the most likely in the outbreak of “general war”.
Officials predicted a barrage of at least 150 missiles falling on the UK, along with an “unknown” number of weapons launched from submarines.
All this is held in declassified documents stored in the Nation Archives.
Russia and Britain remain in a relations nightmare, going tit-for-tat over sanctions including each expelling 23 diplomats from London and Moscow.
Putin won the presidency for another six years on Sunday as his row with Britain deepens, dismissing all accusations against him and Russia.
UK officials have pointed the finger at Moscow of attempting to kill Skripal and his daughter Yulia, 33, using military grade chemical weapon Novichok in Salisbury.
Daily Star Online previously revealed UK defence chiefs warned of a “real risk” of war between Russia and Britain amid rising tensions with Putin.
Correction
In an earlier version of this article the word ‘radius’ was used to calculate the theoretical damage zones that a Russian Tool (ss-25) single 800kt warhead would produce. The article originally used the word ‘radius’ to give the measurement to the thermal radiation radius. The use of the word ‘radius’ in this context was not accurate. In fact the thermal radiation blast radius would be 6.9 miles which would affect an area of 384km2 (square kilometres) or 148 square miles (mi2).
