These open thirds had 64 seats arranged 2+2 in one large saloon. Originally built as tourist stock, they went into excursion and relief train sets with the advent of the steel panelled tourist stock from 1935. They often ran in trains with the corresponding open brake thirds to D196 (Comet Models E30S). D186 were originally fitted with bucket seats whilst D302 had conventional seats with no central armrests. D186 were converted to this style from 1946 onwards.