On Saturday June 29, 1968, at 2.35pm, a special steam train was flagged away from Keighley station up the steep gradient of the Worth Valley to Ingrow, then Damems - one of the smallest stations in the country - into Oakworth and Haworth before finally reaching the terminus at Oxenhope.
It was the first official train to grace the new privately-owned Keighley & Worth Valley Railway since the line's closure in 1961 by British Railways.
And it marked the culmination of six years' hard slog for the society formed to rescue the line for posterity.
Forty years on, the railway is holding a series of events to celebrate the anniversary including an exhibition at the Museum of Rail Travel, Ingrow Railway Centre, charting the railway's rise from the ashes.
The exhibition, organised by the Vintage Carriages Trust, was officially opened on Saturday by Keighley town mayor Councillor Brian Hudson.
Stars of the show are ex-US Army locomotive No 72, one of the two steam locomotives that hauled the re-opening train back in 1968, and one of the original carriages. Both have been specially restored to their distinctive 1968 liveries.
Meanwhile a special steam service from Keighley out on the main line and across the legendary Ribblehead Viaduct in June will be the first time the heritage line has accomplished such a feat, running direct through steam train services on to the main national network.
Sam MacDougall, operating chairman, said: "Even prior to the line's closure, direct services had never gone beyond the junction with the main line at Keighley, except for occasional seaside excursions to Morecambe, Blackpool and Cleethorpes."
The service will be one of the high spots of three days of lavish celebrations, from June 27-29, which will see thousands of people converging on the five-mile line from throughout the country and abroad - many enthusiasts keep a special place in their hearts for the line as it provided the backdrop to the filming of the Railway Children in 1970.
They will have the rare opportunity to travel in some of the line's most antique rolling stock restored by the Lancashire & Yorkshire Railway Trust and Vintage Carriages Trust at Ingrow.
No fewer than 11 steam engines will be in operation during the gala and a special pullman will arrive from London on the Saturday. On the Friday the 1968 reopening ceremony will be re-staged by The Platform 4 Theatre Company, telling of the struggle to save the branch line.
Mr MacDougall added: "This spectacular gala will set the scene for the next 40 years' operation of our railway which has become famous throughout the world as one of Yorkshire's leading tourist attractions."
Gala co-ordinator Julian Jones, said: "Now, after carrying more than five million passengers and seeing the tracks graced by more than 100 different steam locomotives and many heritage diesels, it's time to celebrate."
The exhibition will be open from 11am-4.30pm every day until the end of October. Further information is available at ingrowrailwaycentre.co.uk. For more about the June gala visit kwvr.co.uk or phone 01535 645214.