Yesterday, Prime Minister Boris Johnson said he was considering tightening border controls with France meaning arrivals to the UK from the country could face compulsory hotel-quarantine. Amid the row, once secret files have come to light revealing Downing Street once put together contingency plans to blow up the Channel Tunnel during the Cold War. Now tucked away in the National Archives at Kew, the once-secret plot was drawn up by civil servants and senior military officials in March 1969, while plans for the tunnel were still being drawn out, and were devised in case of a Soviet invasion.
There would be a certain amount of “collateral damage” to Kent, Ministry of Defence (MoD) civil servants claimed.
And the cost was set to be astronomical if officials chose to carry out the secret plans.
Harold Wilson’s Government was also told to keep the plot a secret from France, according to a letter from the MoD advising that explosive demolition ideas “should be covert and classified not less than secret UK eyes only”.
But an atomic bomb would be “100 percent effective” at ensuring a “totally irreversible total collapse, rupture [of] tunnel and sea bed to cause total flooding and complete collapse of part of tunnel”.
The secret memo contained no detail of when the plan to include a nuclear weapon was dropped.
It was discussed further in 1974 when a nuclear weapon was the 14th and last option in an escalating series of contingencies which started at cutting off power to the tunnel.
As Britain was trying to win membership of the European Economic Community – the precursor to the EU – it warned: “For overt preparations to be made to destroy our only link with France and the remainder of the Continent … when the UK is endeavouring to become a member of the Common Market and to convince continental Europe that we have shed forever our island mindedness?”
Former MoD official, Michael Legge, is also quoted as saying: “The tunnel would be virtually unscathed by an explosion of very great magnitude.
“But that ‘total collapse’ could be assured with an atomic weapon. The concern appeared to be that the United Kingdom was protected by a natural moat, the English Channel, and any attempt to maintain open borders at a time of Soviet invasion could be devastating.”
Current contingency plans for the tunnel are protected by modern day national security and secrecy rules.
The idea of a tunnel under the Channel was first mooted in 1802 when Albert Mathieu-Favier suggested a passage for horse-drawn carriages.
Asked whether the building of the current Channel Tunnel involved plans for disabling it in the event of an invasion, a Eurotunnel spokesman told The Independent in 2017: “There has always been a military aspect to it, but I cannot give any further insight into what plans may or may not exist.”
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Winston Churchill’s grandson, Tory backbencher Nicholas Soames, also backed Mr Johnson’s proposal at the time, and said: “It’s an absolutely excellent idea.”
Bridge designer Ian Firth, a past president of the Institution of Structural Engineers, said a bridge over the Channel – possibly with a stretch of tunnel in the middle to avoid having an impact on one of the busiest shipping lanes in the world – was not as far-fetched as it may have seemed.
Despite the enthusiasm, Mrs May’s official spokesman repeatedly declined to offer support for the idea.
France’s finance minister, Bruno Le Maire, also appeared to be lukewarm about the concept of a bridge.
He told Europe 1 radio: “All ideas merit consideration, even the most far-fetched ones.
“We have major European infrastructure projects that are complicated to finance. Let’s finish things that are already under way before thinking of new ones.”