"Steam ... it is addictive," Art Deco Trust events manager Peter Mooney said as he ticked off another of the 2579 seats available for the big weekend's steam train outings.
Of the six scheduled journeys between Friday and Sunday, three have sold out and the others are filling fast.
"This is the ninth year the steam trains will have run during the big weekend - they have become a strong part of it all because they really touch people," Mr Mooney said.
One woman who approached him last year described it perfectly. "She said the engine was a living, breathing thing and, when everyone got off at Holt's Bush, there was nothing anywhere to say it was not a scene from the 1930s."
Mr Mooney and the trust's general manager, Sally Jackson, hoped the train trips would continue.