The plan to join the British Isles to the European continent by boring a tunnel under the sea between Dover, England, and Calais, France, was originally proposed in the second half of the nineteenth century. The bill authorizing the works was rejected in1883. The plan was again proposed in 1930 by many enthusiastic supporters. The tunnel was to be the longest ever made and an engineering wonder. However, the estimated cost, the military risks, and the doubts as to the feasibility of construction led to the rejection of the proposal on June 1930. Finally, in the 1980s, the proposal was accepted and tunneling began.

The plan to unite the British Isles with the European continent was proposed three times.