These chiles have an incredible heat to them. Your eyes can sting from just from cutting one open.
The heat has been measured at 876,000 Scoville units. Further tests have pushed that number to 976,000 units, and beyond 1,000,000. The previous record holder, at 577,000 units, was the Red Savina Habanero. (Compare to Tabasco Sauce, with a heat of 1,500 – 2,500 Scoville units.)
Some suggest just putting a whole Dorset Naga Chile on the side of your plate, and touching your food with the chile from time to time.
The Dorset Naga Chile was developed by Joy Michaud.
She and her husband run a mail-order pepper business called “Peppers by Post” in West Bexington, Dorset.
They bought a hot Bangladeshi chile, called “Naga Morich” from a store in Bournemouth. They extracted the seeds, grew them, and crossed the resulting generations of plants several times with other chiles over a period of several years.
“Mrs Michaud said: “We weren’t even selecting the peppers for hotness but for shape and flavour. There is an element of machismo in peppers that we aren’t really interested in. When the results of the heat tests came back I was gobsmacked.” 
It was released for sale around 2004 / 2005.
 De Bruxelles, Simon. The chilli so hot you need gloves. London: The Times. 1 April 2006.
Day, Sonia. Pepper born in England is no sissy. Toronto Star. 29 April 2008.
Savill, Richard. Dorset claims world’s hottest chilli. London: Daily Telegraph. 4 January 2006.