The bus - PD28 was one of the ex Southdown Motor Services Leyland Titan PD3/4s that CMB purchased to operate on the cross-harbour routes. The opening of the first cross-harbour tunnel in Hong Kong in 1972 generated tremendous demand in passenger traffic and ex UK buses were purchased as a stop-gap measure for fleet expansion when British Leyland ceased the production of front engined double-deckers, which were the mainstay of franchised buses in Hong Kong at that time.

A total of 76 "Queen Mary" type Leyland PD3/4 were in the CMB fleet, and all had Northern Counties bodywork. The windows were modified, unlike those on the model, to full depth sliding type to suit the warm climate. PD28 originally had a 1958 UK registration of TCD 827. It was first registered in Hong Kong on 30th January 1973 and was scrapped in September 1981.