The union flag at the fete is upside down.
There's some music playing at the party that uses the same unusual chord progression as Radiohead's "Creep". The same progression was used in the Hollys' 1972 "The Air you Breathe" but it doesn't seem to have been used before that; in fact Radiohead was sued over it. It had apparently never been used in the 60s, when this series is set.