Alresford Hampshire - It's a charity project that aims to bring the golden age of steam back to a Hampshire railway.
A dedicated team of volunteers have been working for decades to restore two giant steam trains and get them back on the rails of a historic railway line.
But membership of the Urie Locomotive Society has been rocked after a police investigation was launched into allegations of missing funds.
Cash is said to have disappeared from the society's coffers in a blow to its "impossible dream" of putting two Eastleigh-built steam engines back on the Watercress Line.
Roger Hardingham, one of the south's best-known industrial historians, has resigned as chairman of the group, its annual general meeting heard in Alresford.
New boss, Mark Pedley, has pledged to continue full steam ahead despite the loss, believed to be around £27,000.
In a letter to members, he said: "Measures to prevent further loss were put in place immediately after the shortfall was discovered and the police were notified. In view of the ongoing police investigation, we are unable to give further details other than to say that every effort will be made to recover the monies. Nothing must be allowed to stand in the way of the "impossible dream" of having 499 and 506 together in steam in 2020, their 100th year."
Mr. Hardingham did not respond to requests for comment on his resignation.
The author and historian has published dozens of books and DVDs on the south's industrial heritage, focusing on railways and maritime history.
He also led a failed campaign in 2009 to bring RMS Queen Mary back to Southampton and helped run exhibitions on the Titanic and Queen Mary.
Mr. Hardingham runs publishing imprint Kingfisher Productions from his home in Osmington Mills, near Weymouth.
The investigation into the missing funds is being led by officers from Dorset Police.
In a statement released to the Daily Echo the force said that it was "investigating an allegation of theft that was reported on Monday, 16 Nov 2015.
"An investigation is now underway," a spokesman added.
"No arrests have been made."
Funded by membership fees, appeals, and second hand book sales, Urie Locomotive Society has spent 43 years battling to restore the S15 trains to the Alresford-based Watercress Line.
The engines were completed in 1920 to haul heavy goods trains and are the oldest surviving models to be built at Eastleigh Works.
A small team of engineers work on the engines every Sunday at workshops in Ropley, near Alresford, with support from around 220 society members.
The charity has received around £2,500 in donations and many letters of support since the loss was announced, Mr. Pedley said.
"It obviously was a hit because we haven't got enough money anyway to do the whole project," he told the Daily Echo.
"It doesn't affect our plans for the next two years, that's good news. We do have a decent chunk of change in the bank. We're frugal, we like looking in skips because you never know what you might find."
He declined to comment on the investigation, but asked whether the charity would pursue its own legal action, he said: "There's been one interview that the police have done with our secretary. I'm waiting to hear from them and then we'll see what they have to say."
The missing funds are understood to be more than double the charity's £10,500 turnover in the year to March, 2014.
They would have been used to "accelerate progress on specialist engineering projects", Mr. Pedley added.
It is hoped the first train, S15 30506, will be back on the tracks in early 2017 with the second in 2020.
Money is alleged to have gone missing from an account used by the organisation to fund general restoration work but funds raised specifically for the restoration of the 499 train are held in a separate account and are not affected.