EVER since I used this column back in February to declare my support for HS2, I have acquired the dedicated services of a number of assiduous constituents who search out news items which throw doubt on the project, and send them to me.

I don’t resent it. On the contrary, it is an important part of our democracy. It is right that politicians are continually challenged about the way they propose to spend taxpayers’ money.

In the last ten days or so, my correspondents have been particularly busy as Alastair Darling, the former chancellor who first authorised the project, has now changed his mind.

Then there was a report by the Institute for Economic Affairs predicting the costs would rise to £80bn.

I have never been a fan of Alastair Darling’s judgement. I still find it incredible that in his last act as chancellor during the post-election period, he signed up to an agreement that would require us to contribute funds to bail out members of the euro.

So I read his article with scepticism: it seemed to me he said little more than that there were other ways to spend the money.

With respect to the Institute for Economic Affairs, it is important to recognise that this organisation is opposed to state-sponsored projects of this sort: it favours free markets over government activity.

Generally, I agree with its approach, but not on this occasion. In any event, the institute’s cost estimates have been calculated by adding in another quite separate potential railway development project, which gave rise to misleading headlines when the findings were reported.

HS2 is not a vanity project and it is most certainly not about speed. The case for HS2 is based on the desperate need for additional railway capacity. The Victorian rail network on which we rely is already being stretched to the limit.

While we remain the eighth largest manufacturing nation in the world, we are trying to rebalance our economy so that we are no longer so over-reliant on financial services.

We have to raise our game in manufacturing exports and, to be competitive in world markets, it is essential we increase the freight and passenger capacity of the transport network.

We could build new motorways or invest to increase capacity at regional airports. But neither of these options will prove less expensive or controversial. I have no doubt that rail is easily the greenest of the options available.

As for the possibility of spreading the money over a series of improvements to our existing rail network, this would improve things but wouldn’t address the fundamental problem of too little capacity.

We are in a global race in which modern transport capacity is a vital component. HS2 is not a luxury, it is an important investment in the prosperity of future generations of Britons.