Pat Flannery wrote:

Airspeed, Armstrong Whitworth, Avro, Blackburn, Bristol,
Boulton Paul, de Havilland, Fairey, General Aircraft, Gloster,
Handley Page, Hawker, Miles, Short, Supermarine, Vickers,
Westland.

Percival, Auster, Cierva, Folland, Saunders-Roe, English Electric.
Off the top of my head.

Jim Davis