The idea of a tunnel under the English Channel
had been around for several hundred years, legend has it that William the Conqueror
first looked into the idea of connecting his two kingdoms by land in 1076. Progress was slow for the first 800 years as the French
were still trying to get past the stage of deciding what side of the tracks the transport should drive on.
Napoleon looked into the first plans ever of a combined Air (by balloons), Sea and Land (by tunnel) invasion to defeat the Nation of Shopkeepers, but couldn't be bothered to wait the 20 years it would take to build a tunnel to have a pop at the Rosbifs.
In 1906 a rich millionaire francophile wanted to link the Effiel Tower in Paris to a duplicate tower in Crystal Palace, London. He built half the tower, but couldn't get funds to build the tunnel as the bankers and financiers thought his plan was unsound and would be unprofitable for the first 100 years or so. The idea of a tunnel was also looked into by the French and British governments under the new found pre-WW1 spirit of Entente against Germany, however these plans were continually mothballed due to the vast outlay and expense.
Sidenote : IMHO this raises very interesting "What If" scenarios, for instance if the Chunnel had been built in 1906 - 1914 then what effect would a land connection to the continent have had on the course of the World Wars?! What if the Nazis had reached the Calais (as they did) Chunnel entrance whilst the defeated British Army was stranded and encircled at Dunkirk? The image of endless Nazi soldiers piping up the tunnel to Dover within 30 minutes (and London in 90) isn't that nice.
The next and final time the issue of a "Chunnel" was raised was at the Anglo-French summit of 1985 - this summit was one of the more frosty encounters between the French and the English. A senior civil servant once said that Margaret Thatcher and Francois Mitterand had so little in common to talk, let alone agree/negotiate about, that Mrs Thatcher raised the possiblity of a Chunnel for lack of any other diplomatic substance. Suprisingly for the first time since Suez Canal Invasion the French agreed with the English. However it is probably unlikely this is based on the cruel English rumour that the French government really wanted the Chunnel so they could scram to London in half the time whenever the Germans next decided to invade. Preliminary work began very soon after the signing of the Chunnel Accord.
Scheduled to be completed in 1992, it was finished 3 years late thus being perfectly on time according to British train timetabling authorities.
And so for the first time since the last Ice Age, 10,000 years ago England and France were connected by dry soil. Sadly this has not in any way brought in a new age of co-operation and tolerance between the oldest of international enemies. Quite the reverse, perhaps starting from the fact the English either by sublime
thoughtlessness or for their love of not-so-subtle irony decided that the French trains would arrive at Waterloo Station (it being the most glorious monument and building to one of the numerous defeats of France in a war). The French seem to have responded by employing train staff with the most despondantly existential attitude in humankind (motto - "I think, therefore I am, therefore you ain't"). Thus the English sabotage (french word) the superfast French trains by postponing the upgrading of the train tracks until sometime in the space year 2150AD - and so the game continues.
All in all the Channel Tunnel was the longest underground tunnel in the world at the time (it is now second to the Seikan Tunnel), and probably has no equal in terms of a single engineering project in terms of impact of the political, economic, and cultural ramifications.