When you travel to other countries on business, you realise just how useful well-integrated rail links to airports are. Fly into Charles de Gaulle in Paris and you can catch the TGV right there to cities across France, including Lyon and Nice. Land at Geneva airport and you can catch trains to destinations across Switzerland and even to international cities such as Milan, all without having to change trains en route.

Airport rail links at British airports are poor in comparison. Heathrow, the country’s busiest airport, has a dedicated rail link but it stops 15 miles away at Paddington. The Crossrail project, if it eventually gets funding, will improve the situation, linking Heathrow to destinations to the east of London, but is unlikely to appear any time before 2015.

Some people are thinking about integrated transport links. One unlikely proposal currently being discussed by councillors in the London Borough of Hillingdon and by users of Heathrow is a feasibility study on extending the Metropolitan line to the airport.

More concrete plans for airport links are moving forwards elsewhere. This week, Members of the Scottish Parliament approved plans for the Glasgow Airport Rail Link. Trains using the link, set to be operational by 2010, will call at Paisley Gilmour Street before arriving at Glasgow’s Central station. But it stops there. Glasgow’s Crossrail scheme, which would allow trains to cross from north to south and east to west through the centre, remains some way off. The scheme, which is estimated to cost up to £187 million, would mean that Glasgow International and Prestwick airports could gain links across Scotland.

Another ambitious rail link for Edinburgh’s airport is also going through the Scottish Parliament. This link, if approved, would potentially allow direct trains to run from the airport to Glasgow, Aberdeen, Perth and Inverness and maybe even cities in northern England.

Gatwick, Luton and Manchester are perhaps the exception to the rule. The first two have First Capital Connect services that run through the centre of London and look set to be extended when the Thameslink 2000 project (both parts of whose title are now obsolete) finally goes ahead. Manchester has always had decent links across the north of England.

In the current environment, integrated air and rail links are unlikely to be a high priority. Why build an expensive fixed rail link when a no-frills airline can start up a service with little investment?

The thing is, we are probably going to need both. And if plans to extend emissions trading to airlines come into force the no-frills airlines might start to think twice about new regional routes.

So when we all start talking about air travel expansion, let’s start thinking about integrated rail transport at the same time.