The 16.46 from London Euston to Crewe is Britain's most crowded train, official figures have shown.
On this busy rail service, more people are forced to stand than are able to get seats.
The service was 111% over capacity at its busiest point - meaning there were 229 passengers standing and 206 sitting down, reports the BBC.
London Midland said it has since doubled the number of carriages.
The second most overcrowded train was the 07:32 from Woking to London Waterloo, a service run by South West Trains and third was the 07:21 from Oxford to London Paddington, operated by First Great Western.
First Great Western was identified as the train company with the worst overcrowding in London and the South East, followed by London Midland.
South West trains said it was increasing capacity on its service, while First Great Western said it had already added 28 seats.
The figures were published alongside a Government report which showed that 120,000 passengers have to stand on trains into London during the morning peak, or one in five of all those travelling, reports the Telegraph.
24% of morning rush hour train services into London were over capacity and 60% had some passengers standing.
In London, overcrowding was worst at Paddington station while there were also significant increases at Blackfriars, Euston, King's Cross and St Pancras compared with figures from autumn 2012.
Outside London, Sheffield had the most overcrowding, with the average train 2.6% overcapacity at peak times in autumn last year, reports the BBC.
Manchester was second at 1.6%, with Leeds third at 1.5%.
Transport Minister Claire Perry said: "On too many journeys, passengers have to stand in cramped conditions.
"Train operators must act now; they must find new ways to create space on the network and in their trains."
The Rail Delivery Group, which represents Network Rail and rail operators, said: "We recognise that some services remain crowded and understand people's frustration when they cannot get a seat," a spokesman said.
"Because rail users are at the heart of what we do, the industry is already planning to increase peak-time seats into and out of many major cities by a third in the next five years."
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