Our rail fares are among the most expensive in Europe, and they keep going up. Between 1997 and 2010 rail fares went up by an astonishing 66% – well above inflation.

If next year’s planned rail fare rises go ahead, some passengers will hand over up to 15% of their wages for the pleasure of travelling to work.

Since the Labour party introduced above inflation fare rises in 2003, these increases have become a yearly occurrence. Indeed, Labour Party policy is still to have above-inflation rail fare increases every year.

We say that rail fares are already too high. We would cap rail fare increases by RPI-1%, lowering rail fares in real terms. Rail travel is an efficient and sustainable form of transport which should be available to all – and we should be trying to encourage rail use over other transport modes. Fares should reflect that.

Coalition with the Conservatives has meant compromise. This past year saw a rail fare increase of RPI+1%, which is between our position of RPI-1%, and the Conservative proposal of RPI+3%.

But next year, unless we can keep the pressure up on the Chancellor, rail fares are set to rise by the higher rate of RPI+3%.

There is still time for Osborne to see sense. The lower rate for 2012 was announced at last year’s Autumn Statement, after intense pressure from Liberal Democrats in Government and outside, and some Tories, such as the Secretary of State for Transport.

In my role as Co-Chair of the Lib Dem Transport Committee, I’ve kept the pressure up on rail fares the whole time, talking to Ministers and advisors: Lord Bradshaw (the other co-chair) and I wrote to the Secretary of State for Transport earlier this summer to remind her of Liberal Democrat policy, and highlight our opposition to the RPI+3% rate.

We will continue to campaign hard for the Treasury to abandon the RPI+3% rate, and now have the support of several commuter belt Tory MPs – as well, of course, as Lib Dems across the country.

It’s important to remember that part of the reason the fare rises began in the first place is because our railways are very inefficient, and successive Governments have failed to invest when our network required it. Indeed, the McNulty review of the railways, which this Government commissioned, found that they are up to 40% less efficient than our European counterparts.

I’m very pleased that this Government is both implementing the efficiency savings which the review recommended, and investing heavily in our infrastructure to bring down costs in the long-term. £9.4 billion of investment was announced earlier this year. And the Government has committed to electrifying over 800 miles of railway, when Labour managed just 9 miles in 13 years – a shocking failure.

This investment will bring down running costs, and ultimately fares. We’re not making the same mistake that the last Government made; burdening future generations through political short-termism.

But we cannot ask fare-payers to bear the entire cost of this investment, fares are too high already. As the excellent Campaign for Better Transport has highlighted, we risk turning our railways into a rich man’s toy.

I hope that, come Autumn, we will get some movement. Britain deserves an efficient railway, but it must be one which is affordable for all.

* Julian Huppert is Liberal Democrat MP for Cambridge.