First class carriages on busy trains should be removed to ease overcrowding, the Department for Transport (DfT) has suggested following a Telegraph investigation.
Services could be made entirely standard class under a new franchise agreement for routes currently operated by Southeastern, as part of measures the DfT are considering in a public consultation.
The DfT's recommendations follows a Daily Telegraph investigation which found that many first class carriages remain half-empty even in rush hours.
The research, commissioned by the Daily Telegraph in 2013, involved intercity trains arriving at Paddington, Waterloo, Liverpool Street and Kings Cross between 8am and 9am on three consecutive weekdays.
Trains typically had three first-class carriages and five in standard class. Less than a fifth of the first-class carriages were full or nearly full, and some had only three or four people in carriages with 48 seats.
In almost all cases, passengers were standing in standard class carriages, which seat 80 people each.
The new franchise, which will begin in December 2018, could see the introduction of high capacity metro-style carriages on the busiest lines.
It is hoped they would enable a "better balance" of seating and room for standing passengers, space for wheelchairs and pushchairs on shorter journeys and quicker boarding and alighting at stations.
Extending the number of carriages on stopping services from eight or 10 to 12 carriages and providing more seats on high speed services is also being considered.
Some 640,000 journeys are made on 1,900 trains on the lines every weekday, yet only 77 per cent of passengers are satisfied with Southeastern services according to the latest Transport Focus survey, the worst performance in Britain apart from Southern and Thameslink.
The DfT acknowledged that first class seats "remain popular on certain routes" such as the main line to Sevenoaks, Tonbridge and Tunbridge Wells, but said removing them would "create more room for passengers".
Government officials are examining a number of measures which could have a negative impact on some passengers.
They are proposing a reduction in the number of trains that call at some less well-used stations to cut journey times to key locations, and a limit in the choice of central London destinations from individual stations with the aim of providing a more regular and reliable service.
The operator which secures the franchise will be required to form an alliance with Network Rail, which is responsible for railway infrastructure.
Chris Grayling, the Transport Secretary, said: "Services on the South Eastern rail network have been unacceptably poor for far too long.
"Passengers have endured disruption, overcrowding and delays, particularly during redevelopment work at London Bridge station, and they deserve better.
"That is why this consultation is so important. Appointing a new franchise operator from 2018 provides us with a great opportunity to sort out the problems which have plagued the South Eastern network, and deliver the high quality of service that customers expect.
"We are going to do things differently. I want passengers to enjoy more space and comfort, more and better communication with the operator, and a consistently reliable performance."
Mr Grayling announced in December that he would not devolve responsibility for the South Eastern franchise to London's Labour Mayor Sadiq Khan.
He claimed Transport for London's business plan did not offer extra capacity and was simply based on "a belief" that the organisation could run the system more effectively.
But Mr Grayling was accused of putting politics ahead of passengers over the issue after a leaked letter showed he opposed the policy in 2013 as he wanted to keep the network "out of the clutches" of any future Labour mayor.
The DfT consultation closes on May 23 and a summary report will be published in September this year.