During the Victorian and Edwardian periods gentlemen were always for looking for tasteful ways to show off their wealth and refinement. One way to do this was to carry around gold sovereigns; these were worth one pound, and were clearly the classiest way to carry one's money. It was not sufficient to have a pocket full of gold, however. A sovereign case was used for carrying these coins, generally a sterling silver case deigned to look like a fat pocket watch, and decorated with tasteful engravings. Larger cases often took the size and shape of a modern-day cell phone, although there were a number of fancier designs if one was so inclined.
The smaller cases were generally carried in one's waistcoat pocket. This being an era of both innovation and extravagance, it was also possible to buy a combination sovereign case/vesta case, or sovereign case/stamp case. Many cases also had compartments for both full sovereigns and half sovereigns. It was usual to hold 5 or 6 sovereigns per compartment, and some cases were spring-loaded to ensure that the sovereigns were easily at hand when one opened the case.
It is hard to say what the value of a pound in Victorian-era London would be in terms of today's purchasing power, but at a rough estimate each sovereign was worth approximately $100 (that's approximately £ 60 at the time of this writing).