The Duke of Cumberland is a peerage title that was conferred upon junior members of the British Royal Family, named after the county of Cumberland. This gaming token supposedly celebrates George V who ascended as the final King of Hanover. Hanover is located in northern Germany.
Millions of these gaming tokens, also called jetons were made in 1837 and in 1867. The one in our picture comes from a neat metal detecting site Detecting.org.
A quick search of eBay reveals the overall value of these tokens. You will find oodles of examples there selling for a few US dollars retail. If you can find on in superb, almost uncirculated condition, it might sell for $25 retail.
Remember that coin dealers must make a profit to stay in business. If you have one to sell, figure a dealer will offer you about one-half retail value.