In 1933 the Derby Carriage Works of the LMS built a batch of fifteen sleeping cars to lot 699, diagram 1863. At 65ft in length they were the longest eight-wheeled vehicles built by the company. The interior consisted of seven four-berth compartments and an attendant's room. Of LMS 'Period 3' design, these were among the last turned out in fully-lined livery. No. 592 was latterly in use by British Railways staff as a dormitory coach but remains substantially as built.

It was purchased by a QRS and GCR Coach Group member in 1976, leaving Quainton in 1991.