Dark mornings and winter blues have sparked a holiday planning boom which has seen 54% of Britons already booking a summer 2007 break, research showed today.

European mini-breaks have proved particularly popular with 20% of adults planning multiple city breaks this year rather than a traditional two-week beach holiday, according to a survey of 1,000 adults by Yorkshire Bank.

However the spending boom is not necessarily a sign of healthy post-Christmas bank balances. Of those making bookings this month, around a third are using credit cards to secure their holidays on visits to travel agents. Meanwhile a third of those planning a European short break said they did not intend to buy holiday insurance for their trip, according to the survey.

A spokeswoman for the Association of British Travel Agents (Abta) said a high level of holiday bookings was set to continue through the year, with the number of breaks per year on the rise and a trend towards last-minute deals.

“The trend in recent years has been towards a later booking market and people are booking closer to departure. So although January is still a peak booking month, we are still seeing the majority of holidays being booked later," she said.

“Generally the number of breaks people are taking is going up. We are a nation of holidaymakers.”

Abta did not expect holiday bookings to be affected by high inflation rates.

“Holidays tend to be recession proof,” the spokeswoman said.

Earlier this week, another report forecast that at least 17 million British consumers would book part of their main holiday via the internet.

According to the 2007 Holiday Online Planning Report from Continental Research, more than 20 million UK adults will use the internet to source information about an element of their main holiday, while sixteen million will use the internet to seek information about short breaks.