According to present plans, you may be able to cross to France by Channel Tunnel in 1978 - official. But after 170 years of hopes and fears in which all plans have been killed by a mixture of claustrophobia and xenophobia, the last major obstacle is a credibility gap. Is it now at last possible that a tunnel will be built?
Horizon visits some of the most complex tunnelling projects in the world today - in America, Japan, Denmark and Mexico - to see how far we have progressed from the glorious engineering adventures of the Victorians towards what planners would like to be able to think of as precise and predictable.
But is it? Just how feasible is that 35-mile hole through the chalk from Britain to France?
