It was the most challenging underground rescue in history, and Thai authorities drafted in more than 90 of the world's finest special forces soldiers.

But the spearhead of the Thai cave rescue operation depended on seven British civilians who learnt their craft exploring the chilly waters of abandoned mines and limestone caves of England and Wales.

Vernon Unsworth

First on the scene was Vernon Unsworth, who is from St Albans but now lives in Thailand.

Mr Unsworth, an experienced diver who now lives close to the caves, was crucial in persuading Thai authorities to bring in UK expertise.

"When Thai Navy Seals went into the cave but they could not see anything because the water is so muddy so they came back, Chaiyon Srisamut, a friend of Mr Unsworth, told the Daily Mail.