From: A History of the Railways of Oxfordshire, Part 1: The North by Bill Simpson, page 116:
The service between Bicester and Oxford was improved further with the introduction of a steam railmotor service on October 9, 1905. The steam railmotor was a new type of vehicle, a coach body enclosing a small steam locomotive. As a unit it ran in both directions without turning having driving controls at each end.
Part of the new service was the opening of six low platform timber Halts between the termini. The motor vehicle was fitted with steps for these. They were at Wendlebury, Charlton, Oddington, Oxford Road, Wolvercote and a year later at Summertown Halt (renamed Port Meadow). It seems that the LNWR were keen to see if by bringing the service closer to the villages they could siphon off some of the carrier traffic to the stations.
The vehicle was not a great success, it required full staffing with driver and fireman and conductor/guard but could not take up any greater capacity by attaching extra vans or coaches. The system was to find much more success in the push-pull auto train form using conventional tank locomotives with the scope for enlarging the train.
The Halts remained in use until the service was suspended due to wartime austerities this happened on Janury 1, 1917. They reopened on May 5, 1919 but all finally closed on October 25, 1926 when the road omnibus was competing successfully to regain passengers back to the road