Passengers are being urged to have their say on changes to the King's Lynn to London rail timetable, which could see 10 minutes added to the journey.
A number of changes have been made to the timetable, including an additional stop at Cambridge North.
The Fen Line route currently runs in 1h and 40min, but the proposed changes could add 10 minutes to the journey.
The changes are due to be implemented in 2018 but passengers can contribute to the consultation which closes at 5pm on Thursday, July 27.
South West Norfolk MP Elizabeth Truss said: 'I spoke to Govia Thameslink, the rail operator on the Fen Line route, and raised my concerns about the extended journey times and removal of services.
'The proposed retiming of trains at the end of the school day will impact on students and the loss of an early morning train means that there is an hour gap between 0632 and 0733.
'Although the additional stop at new station Cambridge North will add three minutes to journey times, it is nevertheless a welcome addition on the line due to the significant employment opportunities there.'
But Ms Truss added that at least an additional four to five minutes has been built into the timetable to allow for longer stopping times at stations and for what is being referred to as 'resilience' in the programme.
Govia Thameslink highlighted the fact that one of the reasons for the changes to the timetable was to accommodate the new cross rail service in London.
When fully operational there will be direct trains every day of the week from Cambridge to Gatwick, Heathrow, Farringdon and Ashford International.
Ms Truss added: 'This is very good news for rail passengers but I want to ensure our current provision is improved and lengthening travel times by an average of eight minutes is not good news for rail passengers in our region.
'I would urge commuters to contribute to the consultation before it closes this week.'
Govia has introduced new trains on the Lynn to London line, with plug sockets, larger tables and free wifi for passengers.
Passengers can contribute to the consultation and find out more about the timetable changes on www.transformingrail.com
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