First talks about creating the railway took place in Haywards Heath in 1959
Four elderly men who thought up the idea of the steam-powered Bluebell Railway while they were students have gathered in Sussex 50 years on.
Alan Sturt, Martin Eastland, Chris Campbell and David Dalimore set up the original meeting where plans for the railway were discussed.
First talks about creating the railway took place in Haywards Heath in 1959.
The railway opened a year later and now runs for nine miles from Sheffield Park to Kingscote, to East Grinstead.
A grand reunion took place at Sheffield Park Station on Wednesday.
Mr Eastland said he remembered building the railway as "quite a task".
He said: "We were still teenagers, and it was one hell of a learning experience. But we struggled and we got there."
£4m extension plan
The four men travelled on a specially-chartered train with the president of the Bluebell Railway Preservation Society, Bernard Holden.
One of the four founders, David Dalimore, lives in Canada and has only visited Sussex very occasionally in the past 50 years.
The Bluebell line was connected to the National Rail network earlier this year.
A £4m project is under way to extend the Bluebell Railway, which currently runs for nine miles from Sheffield Park to Kingscote, to East Grinstead.
Work to extend the line began last year and if fundraising goes to plan it should be completed in 2010, with steam trains entering East Grinstead over the 10-arch Imberhorne viaduct.
Talks got under way in 1959 to plan the Bluebell Railway and it opened the next year