Whilst Harold Wilson was famous for smoking a pipe, it was in fact largely a prop to appeal to working class voters; in private, as depicted accurately in this series, he would smoke cigars.
When Harold Wilson talks about "Wedgie Benn" he's referring to Tony Benn, who was born Anthony Wedgwood-Benn.
While the Stonehouses are sitting around the kitchen table, the adults are drinking from the old style green bottle of Mateus Rosé. The slightly fruity and effervescent wine from Portugal was, in the 1970s, the best selling wine in the world. The oddly-shaped bottle and distinctive label are instantly recognisable.