Thanks for that I knew I had seen another post somewhere about its use, thanks for flagging it up I have included an edit in my original post above.

Not sure if you have seen my entries on semg and srlhcs but additional to what Chris has stated …set 103 had the set numbers on the end of the SO…photo in the King book.
Also S1314S was allocated to SED boat train number 8 in 1957…I have this in a table of the SED boat ‘sets’…although they were frequently changing vehicles to suit. The rest of the formation of boat train number 8 I have put on the two above Yahoo groups.

It was a loose coach up until November 1959 when it did indeed run in set 104 with Maunsell diag. 2401 brake compo No. 6589. Hornby have made diag. 2401 though not yet with the appropriate running No. for set 104.
Set 104 was disbanded in June 1962 and 1314 reverted to lose stock. It was withdrawn in November 1962.
Although Hornby have chosen to add the set number on the end there is some discussion if this was actually applied to the ends of SO in all the 10 or so BCK / SO sets formed in 1959.

The coach on the Swanage Railway is Maunsell 2nd class open coach 1381. In 1929 the Government abolished 5% passenger duty on condition that the railway company invested the money in new works and this type of coach was one of the results. Before that Southern coaches were of the compartment type. This was a new design with 56 seats in three saloons arranged in bays of two, three and two. Each bay had four seats facing each other. There was a toilet at each end. It was an open saloon which was pioneered in Britain by Pullman and was common in America and Europe. The advantages were that the coaches were stronger and had large picture windows and end doors instead of doors to each compartment.

The coaches were run a loose coaches often next to a kitchen or restaurant car. Some were converted to run as part of pull-push sets in 1959 but most were taken out of traffic with other coaches over 30 years old in the early 1960s.

The coaches were originally painted in sage green livery like Hornby R4357, in the late 1930s they received malachite green livery. After Nationalisation many were repainted crimson and cream before reverting to a darker shade of malachite green in 1956. 1381 re-entered service in Southern malachite green in May 1985 and was later repainted in BR SR green. In 1993 it was used with M7 30053 and Maunsell brake composite coach 6699 for a photographic charter train to recreate a typical Swanage pull-push train as set 619 of the early 1960s.I have not seen the coach recently but the long term plan is to use it as part of a representation of a Maunsell pull-push set.

Information obtained from Swanage Railway Stockbook 2000 compiled by myself and George Moon who wrote the text about this coach with some changes made by myself. The book is out of print but can be obtained at a reasonable price from Amazon or Ebay.

I don’t blame you. They were showing plenty in stock as of yesterday.