Not a 'British gun' but an English gun - at that time both Scotland and Ireland were also making a goodly number of guns.
Thos. Bushill was a gunmaker and gun component maker, listed in the 1849 Gun Trade directory as being based in ct5, New Canal Street Birmingham. 'ct5' means a very small workshop, actually 'court premises number 5' - big enough for a one-man operation, and one of many such shops in the area, which is smack bang in the old gunmakers' quarter.
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