The House (1984)

Set in 1884, and based on the assumption that Britain is one of the Baltic states between Russia and Latvia, making it part of Europe instead of an off-shore island. It is winter 1884. To gain access to the sea, England has declared war on Latvia and believes herself to be winning. But Russia has sided with Latvia and England is doomed. The action takes place on New Year's Eve in a country house on the Anglo-Latvian border. The guests are a cross section of the ruling classes.