A national rail chief has apologised to passengers after a major survey showed dipping customer satisfaction levels.
London and south east passenger satisfaction was particularly low, with services having been affected by a serious flood and continuing work around London Bridge.
The proportion of passengers satisfied with their journey overall fell from 82% in spring 2014 to 80% in spring 2015, the survey of 31,000 rail travellers by Transport Focus (formerly Passenger Focus) showed.
Fewer than half of the 31,000 passengers surveyed reckoned their service offered good value for money, while the proportion of passenger satisfied with punctuality/reliability dipped from 77% in spring 2014 to 75% in spring 2015.
Michael Roberts, director general of the Rail Delivery Group which represents train operators and Network Rail, said: "Too often many passengers are not getting the service they deserve, and for this we are sorry.
"More than almost anything else passengers want trains to be reliable and run on time. After years of improvement overall satisfaction has fallen, largely due to delays in London and the South East and how we deal with those delays."
He went on: "The survey reflects the challenges we face to run trains punctually on an increasingly busy network."
While satisfaction was as high as 96% for travellers on First Hull Trains, it was as low as 72% on Southern and it was only 74% on Govia Thameslink.
Other below-average satisfaction marks included those for Abellio Greater Anglia (75%), Southeastern (75%) and Northern Rail (79%).
The higher scorers included Heathrow Express (94% of passengers satisfied), East Coast (94%), Grand Central (84%) and Merseyrail (91%).
The satisfaction level for London and south east England operators dipped from 80% in spring 2014 to 78% in spring 2015.
The biggest decline in satisfaction on these routes was a 5% dip in those who felt train companies dealt well with delays.
Overall, comparing spring 2014 with spring 2015, two operation companies (Abellio Greater Anglia and Southern) significantly declined in satisfaction levels.
Three significantly improved (Arriva Trains Wales, CrossCountry and East Coast), while there was no significant change in the satisfaction levels for the 18 train companies.
Overall satisfaction on individual routes was lowest for the flood-hit Govia Thameslink's Thameslink Loop service, at just 64%, while only 67% of passengers were satisfied with Southern's metro services.
In contrast, satisfaction on some other routes was as high as 95-96%.
Just 45% of passengers nationwide thought the price of their ticket represented value for money - about the same figure as for spring 2014.
Value-for-money ratings varied from as low as 29% for Abellio Greater Anglia's Mainline services to as high as 81% for ScotRail's rural services.
Transport Focus chief executive Anthony Smith said: "Commuters will not be surprised at these results. Long-term plans and investment are important and welcome - how the work is carried out, though, is crucial.
"The London Bridge rebuilding scheme in particular has caused problems. We're now working with train companies and Network Rail to try and minimise the impact on commuters."
Office of Rail and Road (ORR) chief executive Richard Price said: "Britain's railways have seen a marked improvement in passenger satisfaction in the past decade with growing passenger numbers each year.
"In the past year however we've seen overall scores dip significantly. Passengers are telling us that reliability and punctuality of trains remains their primary concern."
He said the ORR was investigating Network Rail's (NR) performance improvement plans.
Mr Price went on: "We also know that how the rail industry deals with delays is a big cause of passenger dissatisfaction. ORR is concerned that passengers are still unhappy despite recent initiatives."
Mick Cash, general secretary of the RMT union, said: " These figures show that passengers paying extortionate commuter fares are receiving some of the lousiest services while the private train companies are laughing all the way to the bank.
"These private train operators know that regardless of how dire their services, or how blatantly they rip off the travelling public, they will retain their franchises and will escape unscathed. It's a racket and it should be stopped."