Boost for travel agents as Race Across the World grips viewers

A scene from series four, which attracted a million more viewers than the previous series. Photograph: Studio Lambert/BBC

No celebrities, no luxuries and a miserly £20,000 in prize money. On paper the BBC One series Race Across the World never looked like a hit.

And yet the travel programme, in which backpackers battle across distant sections of the planet, is now into its fourth season with audiences rising faster than a tuk-tuk driver can get you down Bangkok’s Khao San Road.