Blotto, Twinks and the ex-king's daughter

It's that glorious period between the two world wars, and the exiled king of Mitteleuropa is visiting the ancestral home of the Duke of Tawcester. When the ex-king's daughter is kidnapped, noblesse obliges the Duke's handsome, brave, and rather stupid son (known to all as Blotto) to drive off to the rescue. Luckily, he's aided by his brilliant sister, Twinks. Plus, he's got a really swell car.