According to my 1971 edition of 'The Observers Book of Commercial Vehicles',(foreword by Piet Olyslager), Unipower was a company; "Unipower Limited" of Aintree Road, Perivale, Middx
This was also the case in the 1974 edition, and by the 1978 edition, AC Cars Ltd of Thames Ditton were the owners.
Whilst I accept they were originally 'Universal Power Drives', by the seventies and the time of the vehicle I posted the picture of they were trading as Unipower.