East Anglian MPs have restarted their efforts to lobby government for investment in the region's rail network after suffering a set-back in the recent ministerial reshuffle.

Campaigners from the East of England had gone to great lengths to successfully persuade former transport secretary Justine Greening that the Treasury should invest to transform the East of England's rail network.

Their push had already seen the government approve funding for improvements to the Ely North Junction, a key rail bottleneck in the region, but that upgrade was only the first step in a series of measures campaigners want.

Now they must persuade new transport secretary Patrick McLoughlin of the case all over again, with the Treasury's coffers as strained as ever.

In particular they will ask him to endorse the East Anglian Rail Prospectus, a document setting out improvements needed over the next two decades in order to allow the Eastern region to develop economically.

After a meeting between regional MPs and Mr McLoughlin, Norwich North MP Chloe Smith said: 'It's important to make sure that the new secretary of state knows what we are asking for on people's behalf.

'I asked for a meeting straightaway to present the prospectus before the Norwich-London franchise process starts in the autumn.

'He listened and praised our campaign for getting stuck in early and acting together. We put the case for strategic investment in the East Anglia rail network over the long term.'

The prospectus outlines a string of investment priorities to be carried out between 2014 and 2019 including the remodelling of Bow Junction near London Liverpool Street, improving freight capacity and upgrading rolling stock.

Ms Smith added: 'We got early successes in the rail statement in July – including investment for Ely North – but the campaign continues now with focus on the Norwich-London line.

'We believe there is a powerful case that with appropriate investment for better rail links – especially between our key science and technology clusters in Norwich, Cambridge and Ipswich. East Anglia can gain substantial economic growth. We want East Anglia to get the rail deal it deserves.'

Looking towards the long term the prospectus also calls for the electrification of lines in the region and much faster intercity services.

But there are also questions over whether the new transport secretary might seek to boost his party's electoral hopes, with the 2015 election coming into sight, by investing more in areas with marginal seats rather than the safer constituencies his party has in Norfolk.

Broadland MP Keith Simpson said: 'One has always got to take account of the politics. The transport secretary can't invest in something just because it's to the advantage of the coalition.

'But there might be an element in his mind that notices that, along the entire stretch between London and Norwich, there are marginal seats that might be affected.

'Ultimately the case that we have will stand and fall on its own merit. We have a very good case, not just from the point of view that we want reliable trains, but because it meets the government's criteria in terms of addressing things like economic development and social degradation.'