A-Class yachts are large and heavy. They were given Classic Class status in 2004. Although they are not limited in length, they are controlled by a formula, devised in 1922 by Major Malden Heckstall-Smith.  This balances waterline length, displacement, and sail area. Thus, sail area is reduced as the displacement reduces and as waterline length increases.
The Highlander A-Class was also developed by Gavin Britt and club members.
These yachts look magnificent on the water, but are awkward to handle both on land and in the water.