"Many people buy or breed cobs which although of show quality then grow above the maximum height for cobs of 15.lhh," said Hickstead's show director Roger Stack.

"This will get them on to the show circuit and offer the chance to compete at the Royal International, which is the ambition of most people interested in showing."

The British Show Horse Association has said it supports the move as part of its drive to increase membership and make showing more popular.

Qualifying classes for maxi-cobs will be held at shows around the country, with winners going forward to the final at Hickstead in July 2009.

"All the accepted rules and standards will apply to the series," said Mr Stack.