There is a sketch in Bradley’s book, perhaps the same as you used. When the SER became independant of the Croydon and Brighton loco committee, they went through a phase of long boiler engines, and this one was part of the goods design in 1845, six from Nasymth, 95-100, and four from Tayleur, 119-122. The Canterbury and Whitstable had opened with stationary engine haulage for most of the length, which proved unsatisfactory, and the line was taken over by the SER and rebuilt for loco haulage throughout. 120 and 121 went to work the section. All the class had boiler rebuilds later on, 121 wasn’t scrapped til 1883, when it was working at .