The opening of a new railway station in Cambridge should be the spur for longer trains to run from West Norfolk to the city and beyond, campaigners have claimed.
Pressure is building on ministers and industry bosses to find ways of increasing capacity after a key upgrade was delayed in November.
A feasibility study into whether eight-carriage trains can run to and from Lynn, instead of the current four, is being undertaken.
But, with a new Cambridge North station due to open next spring, campaigners are calling for a solution to be finalised before then.
Andy Tyler, secretary of the Fen Line Users Association, said: “That should be the spur so we can have eight-car trains that stop there.”
Rail officials announced last week that services would not begin at the new station, which will serve the city’s science park, until May 2017.
The opening had previously been scheduled for this December and the delay was greeted angrily by political and business leaders there.
But, while the impact of the additional stop on timetables is still being assessed, politicians and campaigners are keen to keep up the pressure for service improvements, amid continuing growth in passenger numbers.
Mr Tyler said; “If we have longer trains it will relieve the current overcrowding.”
Figures last month showed more than 1.6 million passengers used the stations in Lynn, Downham and Watlington during the year to the end of March 2015, up almost seven per cent on the previous year.
FLUA officials have also backed calls for a new station on the southern edge of Lynn to accommodate demand.
A summit will take place in Downham next month following Network Rail’s decision to halt work on an upgrade to the Ely North junction until 2019.
But ministers insist there is money available to expand services by enabling longer trains to run before work on the junction is carried out.