Anybody thinking of getting in on Ryanair's £19.99 flights to Britain may be in for a disappointment. The price war on the London air routes spawned acres of positive newsprint but there must be a question of how much customer goodwill it will generate.

There are likely to be some disappointed customers. At least one person found that the fares were sold out by lunchtime on Wednesday for any flight next Monday.

Others reported that the lines were constantly engaged as they tried to get through to the booking number.

There is also doubt over whether £19.99 for a one-way ticket is economically viable. After all this makes it cheaper than many inter-city train journeys in this country and even the ferry from Dun Laoghaire to Holyhead.

The next closest competitor to Ryanair on the route is Aer Lingus at £99 for two people travelling on the same return journey. That level of discounting has got to raise questions about the long-term viability of such cut-price offers.