Unions today pledged to fight to bring more work to the Springburn rail depot in Glasgow as the last refurbished train rolled out of the plant.
The completion of a contract to upgrade a fleet of ScotRail trains means the site is due to be mothballed, with the last 67 of the 200-strong workforce losing their jobs.
However, it is understood Gemini Rail Services hopes to attract work from other rail firms, such as Wabtec, Brodies and CAF.
The firm's lease at Scotland's oldest rail works expires next March, although unions fear it may be ended in September.
The last train to leave the yard today was marked by the workforce, waving banners and flags, parading out of the site, led by a piper.
Glasgow North East Labour MP Paul Sweeney, who addressed them, said: "There is opportunity on this site - skills and motivation.
"I'm sick of hearing about decline", and said the works had made a £4 million profit last year.
He described Gemini as an "industrial asset-stripper" for deciding to centralise work at Wolverton in Milton Keynes.
The difficulties of finding a future for the 163-year-old site reflect the complexity of the largely-privatised train side of Britain's railways, which Scottish ministers said meant they could not step in to take it over.
It depends on work from rolling stock companies, which own the trains that ScotRail and other operators run.
Springburn's final contract, for ScotRail Class 156 diesel trains, which run on routes such as the Glasgow-Mallaig line, was with owner Angel Trains.
The site has also done work for Angel on ScotRail's diesel High Speed Trains, such as for the Edinburgh-Aberdeen route, and on the operator's Class 318 and 320 electric trains, which run around Glasgow, for owner Eversholt.
ScotRail said: "As the rolling stock is ultimately owned by the leasing company, they decide where work is carried out. ScotRail has no direct control over this."
A Scottish Government spokesperson said: “This is a disappointing day for Scotland’s rail industry and we wholly empathise with the remaining staff and their families.
"We appreciate the engagement and resolve shown by those involved in efforts to keep this depot open.
"That is why Scottish Enterprise remains committed to doing all it can to look at the potential of re-purposing the site to ensure a sustainable future.
“We reaffirm our belief that the timescale set, especially as Gemini has now progressed to closure, was too short to allow for a meaningful review of options for the site.
"The Scottish Government is unable to nationalise the site due to state aid rules and challenges from other companies who offer the same service.
"The decision to award work to Gemini and other maintenance companies lies with rail leasing companies."
Unite and the Rail, Maritime and Transport union (RMT), which represent Gemini staff, said they would fight for more contracts so workers could return to the site.
RMT Scotland organiser Mick Hogg said: "If the Scottish Government can throw a line to Prestwick Airport, it can throw a line to Springburn.
"It makes no sense whatsoever to send trains from Scotland south of the Border [to be refurbished]."
Built in 1856 by the Caledonian Railway as the St Rollox works, and latterly known as the Caley, the site once stretched to twice its current area, with the northern part now occupied by Tesco Extra, Lidl and Costco stores.
Labour leader Jeremy Corbyn tweeted a campaign video for the site: "The Caley rail works is a national asset which provides jobs to a proud community. It must be saved."
Gemini declined to comment today.
It announced the closure in December and said in March the decision was due to "severely adverse market conditions".
“Following this difficult decision, the company will proceed with a gradual closure programme, completing existing projects before our final exit in March 2020.
“Gemini will continue to work with the Scottish Government and stakeholders over the site’s future use, including the possibility of a transport hub.”