John Denis Martin Nunn is an English chess grandmaster, a three-time world champion in chess problem solving, a chess writer and publisher, and a mathematician. He is one of England's strongest chess players and was formerly in the world's top ten.

The British Chess Championships are organised by the English Chess Federation. The main tournament incorporates the British Championship, the English Chess Championships and the British Women's Chess Championship so it is possible, although it has never happened, for one player to win all three titles in the same competition. The English Women's Chess Championship was also incorporated into this event but did not take place in 2015 and was held as a separate competition in 2016. Since 1923 there have been sections for juniors, and since 1982 there has been an over-sixty championship. The championship venue usually changes every year and has been held in different locations in England, Scotland, Wales and once on the Isle of Man.