Who is Mr. Fowler from The Great Train Robbery and what is their importance?

Mr. Fowler is the general manager of the bank that provides the gold for the payments of soldiers in the Crimean War. Because of his position, Mr. Fowler is trusted with one of the keys to the Chubb safes in which the gold travels. Mr. Fowler wears the key around his neck and takes it everywhere. Sadly, he also brags about his position, and it is from Mr. Fowler that Pierce learns about the four keys and their locations.