This is partly because it is a more fragmented market with millions of suppliers, from bed and breakfasts to five-star hotels to package holidays.
Holidays involve far more complex decisions, and are a bigger purchase.
The average expenditure on a holiday is 400 per person and the average number of people travelling is two adults and maybe a child. So a typical outlay is 1,000. But they are wary when it comes to their main holiday. Another obstacle, says Brooks, is that there are relatively few travel agents online that offer a good range of services including flights, trains, hotels and so on. There are websites offering plenty of information but not full online booking.