First Great Western (FGW) has been exposed as operating one of the most overcrowded trains in the South East.
The company topped a list of the most packed services in 2006, published by the Department for Transport.
Last week passenger watchdog London TravelWatch called for the government to review the FGW franchise, saying the firm provided an "abysmal service".
FGW said the figures were a snap-shot of services and their timetable and carriage numbers had since changed.
Punctuality complaint
The figures were collated by a head count being carried out on services in London and the South East one morning last autumn.
A DfT spokeswoman said while the figures give an idea of where there is overcrowding and where more capacity is needed numbers can be inflated if, for example, earlier trains are cancelled.
Top of the table was FGW's 0635 GMT service from Bedwyn to Paddington on which 771 people travelled, despite it having a capacity of 497.
Jo de Bank, from London TravelWatch, said their main complaint was with punctuality and information provision but that overcrowding worsens because of delays.
She said: "London and Thames Valley provision has only a 70% punctuality record which is unacceptable."
In January FGW apologised to rail users "for not meeting expectations" after a protest by hundreds of passengers.
A spokesman for FGW said: "We know that capacity in London and the South East is one of our major challenges as customer demand continues to grow.
"This information dates back to autumn 2006 and we have made a number of changes with the introduction of the December 2006 timetable, providing more seats on some services and retiming others."
He said there would be further improvements with the introduction of a new timetable in December.
hock: Mind you, those are only the worst services - surely some of them have enough room?
