Hi Phil,
HW is one of the registration marks for Bristol and the series started in July 1927. Try contacting Bristol Records Office and see if they have anything. Normally this will at the very least give you where the reg number was allocated but in some instances will give you a great deal more than you bargained for like a first owner….
Information on records can be found here:
https://www.kitheadtrust.org.uk/england_wales2_11.html
Thanks
James
