RICKETY 20-year-old trains are a sign of “yet another industry we’ve allowed to collapse,” Britain’s leading transport historian blasted last night.

The Office of Rail and Road’s study revealed that trains are on average 20.2 years old — marginally higher than the figure at privatisation.

London’s commuters ride on the newest fleet — but they are still 18 years old on average.

Rail union RMT general secretary Mick Cash stormed: “The lack of planning on Britain’s fragmented and privatised railways has left growing numbers of passengers paying the highest fares in Europe to travel on clapped-out, overcrowded trains.”

He said that “rip-off rail companies and rolling stock suppliers” were “laughing all the way to the bank.”

Writer and historian Christian Wolmar said the demise of Britain’s train-building industry should be remembered as troubled steelworks face closures and job losses.

“Train-building was yet another industry that we have allowed to collapse,” he told the Star. It resulted in Britain having one facility left in Derby, owned by a Canadian company Bombardier.”

He said the revelations “ruined” the argument that privatisation would lead to “a massive amount of private investment.

“Investment is ultimately paid for by the government, or by increased track access charges [for private train operators] which are paid by government subsidies or by passengers [through fares].”

Northern Rail’s trains are on average 26 years old, with many routes running the infamous “bone-shaker” units converted from buses as a stop-gap in the 1980s.

“You can’t have a northern powerhouse when old buses are running around on rails in the north,” the Campaign for Better Transport’s Martin Abrams chastised.