For more than 20 years the Prince and Princess von Hessen saw themselves as a happy “McFamily”, toiling away in their four McDonald’s franchise restaurants like something out of a social democratic fable.

The pair had first met in the chain’s Munich branch and their four children practically grew up in its aprons and paper caps, with “ketchup in their blood”. The family kept at it despite the couple’s divorce and the prince’s death in a road accident two years ago.