There are a number of doubles in the BBC mini series "The Flame Trees of Thika" (excellent show and book BTW, gives good insight into colonial British East). From the look of them they are British and medium bore, box lock, possibly an Army and Navy 450 NE. If you really want to see a lot of doubles, rent the Canadian TV series "The lost world". They use doubles exclusively, both back action hammer Jones underlever 450 BPE's and late model box locks of some sort. Interestingly, the show is filmed in OZ, in the northern territory. Also in the 2 hour mini series of same, Lord Roxton carries a Jeffreys 500NE, and comments, "..can drop a charging bull elephant at a 100 yards."

BS