Dula were motorcycles produced circa 1970s.
This firm was involved with grass-track racing and produced frame kits designed to take most of the usual units used for that sport - usually 250cc to 500cc ohv single JAP or Jawa engines.
Sources of Information
The British Motorcycle Directory - Over 1,100 Marques from 1888 - by Roy Bacon and Ken Hallworth. Pub: The Crowood Press 2004 ISBN 1 86126 674 X