The festive season is over, the days are dark, and payday is but a glittering mirage on the horizon. It's no surprise that we all start dreaming of a holiday in January - but is it the best time to book one?

Deciding when to book a getaway is something of a science.

After analysing data from more than a billion searches on their website, travel search engine, Kayak, found that the price of a flight can be affected by a whole range of factors - from how far ahead it is booked, to the time of year. And crucially, it's not always as easy as: "book far in advance" or "avoid the school holidays".

We took a look at what they found. With these canny tips and a bit of careful planning, you could save a small fortune. Bon voyage...

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When is the best time to book a holiday? 10 expert tips on money-saving flights