In the 1953 film of that name, what is "The Titfield Thunderbolt"?

Goodboy, We actually got developed not only the steam train technology to get them all started, in the sixties we developed the Hovertrain using Mag Lev propulsion (Magnetic Levitation) . The government of the day decided it was too expensive so the lead in this technology passed to China and Japan . Then the railways were privatised and profit comes before investment.

how did we ruin the railway advance, other countries are years ahead of us and we started it all ???