In 1966/1968, three cariages were converted to 'Mini-Buffet' service.
This was to provide some refreshment services on long haul country trains.
The class given was 'MBS' and the cars were numbered 1,2 and 3.
The cars were converted from _BS_ carriages.
In 1983, one car reverted to BS; the other two were modified to BRS.