You say that the British army kill bears from Canada, if you look on the link you posted (http://en.wikipedia.org/wiki/Bearskin) it clearly says that the Canadian Army also use bearskin.
This practice is not limited, however, to just these countries Belgium, Denmark, Italy, Holland and Sweden are also listed as killing bears for their fur for use in a militarally cerimonial context.
I suggest that you aim your petition, not to the British Army, but to the Canadian government. If the Canadians are also using bear fur then they will therefore sympathise with the British when it comes to supplying it, if it were to be stopped in Canada then the Canadians may well be less inclined to sell the fur to the British, and undoubtedly the Belgians, Danish, Italians, Dutch and Swedes also.
This practice is not limited, however, to just these countries Belgium, Denmark, Italy, Holland and Sweden are also listed as killing bears for their fur for use in a militarally cerimonial context.
I suggest that you aim your petition, not to the British Army, but to the Canadian government. If the Canadians are also using bear fur then they will therefore sympathise with the British when it comes to supplying it, if it were to be stopped in Canada then the Canadians may well be less inclined to sell the fur to the British, and undoubtedly the Belgians, Danish, Italians, Dutch and Swedes also.