How to fill the time while waiting for a delayed train on the draughty platforms of Luton Airport Parkway, a railway station every bit as appealing as its name suggests? On Monday night, I found an answer: spend it trying to persuade a dozen newly arrived foreign visitors that everything the train operator is telling them is wrong, and that if they follow my advice they will arrive in central London much sooner.

Tourism is an immense force for good – both the freedom you and I enjoy to explore the world, and the economic benefits that visitors from abroad bestow upon Britain. There is much to celebrate. London last year increased its lead as world aviation hub, accelerating away from its nearest challenger, New York. To have more airline seats pointing at your capital than at any other city on earth is a priceless asset, though the tricky task remains of persuading visitors to explore beyond London.

Yet as I found out at Luton Airport Parkway, life for new arrivals is not always easy. Bear with me while I explain how the station works. It is at the foot of the hill on which the Bedfordshire airport perches, with a six-minute bus link going up and four minutes coming down (yes, I should get out more). Non-stop rail services to London's loveliest station, St Pancras, are run by East Midlands Trains and leave from Platform 3. Thameslink stopping trains depart from Platform 1. Thameslink also runs fast trains to the capital, which take half-an-hour to reach St Pancras. Usually they go from Platform 1, but sometimes, as on Monday evening, Platform 3.

To complicate matters, and further baffle foreign visitors, not all tickets are equal. Buy a ticket at the station and you can use it on any train. But those which are sold on board easyJet and Wizz Air flights are valid only on Thameslink. Which is why, I presume, signs around the station insist "Platform 1 for London". Wait long enough, and a train to the capital will eventually turn up, though it may take its time getting south.

Lingering longer than necessary appeals at some stations. Seiano, on the Circumvesuviana railway from Naples to Sorrento, clings vertiginously to a viaduct above a gorge that rushes down to the embrace of the Mediterranean. But we were in Luton, in February, in the dark.

It wasn't the easiest of gigs: yelling across a railway to a group of people who do not have English as a mother tongue and explaining to them that, unless they have urgent business in a stop along the way such as Cricklewood, they should join me on Platform 3. Eventually they gathered up their multitudinous belongings and shuffled up the stairs and over the footbridge.

I then ran over to the ticket barrier (involving a staircase, a corridor and four separate escalators) to suggest the staff tell passengers that, whatever the signs might say, Platform 3 was an excellent place from which to reach London.

"We have been telling them as they come through the barrier," I was told. No one told me, I said. How about an announcement to ensure people heading for London were on the right platform?

"Thank you for your input," I was told in a manner that suggested my input was worth about as much as an expired day return to Dunstable, last served by passenger trains 50 years ago.

Then it went to penalties

When I returned to Platform 3, at last an announcement came through. Oh good, I thought, they're going to reassure this mini-European Union of passengers that the signs are wrong and the person who has been cajoling them is genuinely trying to help. But instead the anonymous voice warned people waiting on Platform 3 that if they took the next train with a Thameslink-only ticket they faced a penalty.

Welcome to Britain, where if you inadvertently board a train with red and orange stripes rather than a grey one, your rail ticket may be the fast track to penury. But in this case the announcer was talking first-class tosh to we second-class citizens. A screen on the platform promised a Thameslink on which any ticket would do.

My credibility among the visitors I had coerced on to Platform 3 sank. Some people started picking up their belongings. My bid to prove that Britain values visitors and wants them to reach their destination as swiftly as possible was getting desperate. To demonstrate my conviction. I guaranteed to the assembled company: "If you get fined, I'll pay it."

Very cross: the Mersey

After this express largesse, I was relieved when the promised Thameslink service arrived and reached London in half-an-hour. Talking of relief, though, anyone using the loo en route was unlikely to be impressed; last month Passenger Focus found Thameslink has some of the worst toilets of any British train operator. Only one in four travellers was satisfied with the on-board facilities. The lowest score in the UK, though, went to Merseyrail, which runs commuter services around Liverpool and the Wirral: 77 per cent of passengers are angry about Merseyrail's toilets. Why are they so awful, I wondered? Simple, said a Merseyrail spokeswoman: "We do not have toilets on any of our trains." But all but 10 of the 66 stations have loos to use.