Here is the prewar 1800:
http://www.earlytelevision.org/hmv_1800.html
Many prewar designs were sold right after the war, with few design changes. Flyback HV supplies were not used in most 1946-48 British sets. Often the same cabinet was used. Here is a summary of HMV before and right after the war:
http://www.thevalvepage.com/tvmanu/hmv/hmv.htm