Since it first launched on BBC Two in 2005, there have been 20 series of the UK version of Dragon's Den – and 19 millionaire investors who have all considered themselves shrewd enough to spot a lucrative business opportunity when it's pitched in front of them.

But they don't always get it right and every so often, the rejects get the last laugh.

Read on to discover the incredible success stories that the Dragons have missed out on over the years.