"Ne oubliez pas votres passports..." I told the girls, quoting the words of Antoine du Cannes in the Eurostar adverts.

We were off for a girls' night out in Lille, though in retrospect Hastings or Bexhill would have proved more sensible choice of location - not being required to pass border checkpoints to enter the lovely seaside towns.

But Lille it was and after hours of organisation - you have no idea how many phone calls, faxes and emails it takes to get six people organised into going away for one night - we were off, first thing Saturday morning.

I had the tickets, I'd booked the hotel, I had the francs, I knew where we were going once we got there, I'd told everyone not to oubliez their passports but I hadn't told them to check that their passports were valid.

And at nine o'clock on Friday evening I got a phone call from Clare; "Err.... bit of crisis," she said. "My passport has run out - do we have to have one?"

"Oh yes," I replied, thinking of Antoine reclining in his comfortable Eurostar seat (actually they don't recline) and pointedly warning us not to "oubliez pas" our passports.

I also cited incident of friend, who tried to go to Brussels for the weekend but forgot her passport and ended up spending the night in a detention centre for illegal immigrants before being sent packing the next morning.

"You definitely need a passport."

And after exhausting the various possible options; such as going to London first thing the next morning to try to get a new passport and getting a later train (not possible because as usual the French were on strike and not selling any more tickets until their dispute was resolved), Clare decided that it seemed unlikely she would be able to come.

Helen, however had other ideas about the necessity of travelling with the correct documentation. "Oh you don't really need a passport," she said breezily, as if we were discussing the weather and whether you might need an umbrella or not.

"I think you do actually," I said, wondering whether between 10pm, which by this time it was, and 6.30am, when we'd be leaving, we might be able to find someone else to make use of ticket and hotel room.

"Not really," Helen went on. "I went to Spain when my passport was about a year out of date and nobody checked it until I got back to Britain and then I was coming home, so they had to let me back in anyway."

And this was not the only authority-defying incident which Helen knew of.

Her mother had been to Portugal on a Bodlean library ticket, her sister had been to France with her friend who looked a bit like her's passport, and her mother's friend had been to Amsterdam with her granddaughter's passport.

She was adamant that passport control was just a formality which could be easily dispensed with.

So we risked it - or rather Clare did - I am such a law abiding citizen I would not even dare get on a train to Preston Park without a valid ticket, let alone try to cross frontiers without all the right paperwork.

We left, with self fully expecting that Clare would be turned back at first hurdle, Ashford international.

In fact nobody even asked us to produce passports there. The ticket inspector on the train, who is also supposed to check passports, didn't bother to check either.

So we disembarked at the other end, sweating and following arrows for the exit from Lille station, imagining that at every corner we would be met by armed passport control officers who would march Clare away and swiftly deport her.

The next thing we knew, we were outside the station and walking towards our hotel without so much as a checkpoint or official having been passed on the way.