Hello there - afraid that I cannot add much that will be of use but I remember being told by an old hand railwayman that LMS banana trains from Avonmouth to London were routed via the SMJ. As for the Karrier Ro-railer (a splendid looking vehicle), it was trialled between Blisworth and the Welcombe Hotel conveying their guests. Incidentally, it had a less flashy brother - a humble lorry version, which was used by the LNER p.way on the West Highland line.