I only know what is in Peter Filby's book Classic Kit Cars published in 1997.
Produced 84-88. Number produced "quite a few"
Price guide in book £900-£3000.
Oldham & Crowther were based in Peterborough and Bromley in Kent try this link to see a pic of a sport like yours.
Must be worth rescuing.
http://www.allcarindex.com/main-inde...ed-Kingdom-OC/