Munster Go Home (1966)

Herman discovers he s the new lord of Munster Hall in England. The family sails to Britain, where they receive a tepid welcome from Lady Effigy and Freddie Munster, who throws tantrums because he wasn t named Lord Munster. An onboard romance had blossomed between Marilyn and Roger, but on land Marilyn discovers Roger s family holds a longstanding grudge against the Munsters. Herman upholds the family honor in an auto race; he and Grandpa also unlock the secret of Munster