Pressure is growing for improvements to north Norfolk's 'economic lifeline' after it was revealed that there has been a surge in the numbers using the booming Bittern Line.

Passengers at the nine branch stations soared by more than 27,000 between 2009-10 and 2010-11 - a ringing endorsement of people's desire to let the train take the strain.

And the figures do not include many of those who use rover tickets, or the thousands whose fares are not collected - so the true scale of the success story of the Sheringham to Norwich line could be greater.

Now rail campaigners are urging train operator Greater Anglia and the government to drive a host of improvements to build on the success - and open the way to more growth.

North Walsham county councillor Paul Morse said: 'I am sure there is more potential in the line and I am particularly keen to see something done about the ticketing and car parking at North Walsham.

'I also feel that there needs to be some improvements in the timetable, particularly in the early morning when people are travelling to work.'

He also called for a half-hourly service between North Walsham - the line's busiest branch station - and Norwich, and later final trains from Norwich, to fit in with cinema and theatre times.

And he said there was a need to provide data to train operator Greater Anglia to prove that such improvements were financially viable.

Ted Gasden, chairman of the Bittern Line community rail partnership, said: 'The fact footfall has increased means there is a need there. The Bittern Line is attractive to tourists but it is also the economic lifeline to north Norfolk.

'There are no motorways or dual carriageways so the railway is vital for people if they want to access better paid employment and a greater choice of education outside north Norfolk.'

He called for more investment in the line, including more carriages, ticket offices at stations and more trains to Norwich before 10am.

He added: 'It is essential to carry out transport improvements if the area is going to develop and rail improvements are much less intrusive than road.'

Cromer councillor Hilary Thompson, who is on the Bittern Line partnership, said that too often the conductors could not get to every passenger to sell and check tickets.

She was also concerned about the state of Cromer station, and the cleanliness of the trains on the Bittern Line.

The Bittern Line is part of the Greater Anglia short-term franchise, which runs from 2012 to 2014. In 2014 the Department for Transport (DfT) will invite bids for a longer franchise - which campaigners hope will encourage significant investment.

Figures published by the Office of Rail regulation show that 768,432 passengers were recorded in 2010-11 at Salhouse, Hoveton/Wroxham, Worstead, North Walsham, Gunton, Roughton Road, Cromer, West Runton and Sheringham - up from 741,050 the previous year.

A Greater Anglia spokesman said: 'The Bittern Line has been a tremendous success story for a number of years and has benefited from several increases in train service frequency reflecting the popularity of the service.

'Through initiatives such as the station travel plan at North Walsham and the commitment of station adopters the route is continuing to thrive.

'We will continue to work closely with Network Rail, the region's MPs, local authorities and other key stakeholders including the Community Rail Partnerships, in making the case for further improvement to train services in Norfolk and the region.'