When Eric and Sharon come into the restaurant, Mr Smith calls them Margaret and Tony. This is in reference to Princess Margaret and her then husband Antony Armstrong-Jones (Lord Snowdon).
Before going to the Young Conservative's barbecue, Dennis asks "who's this Enoch they all keep talking about?". Enoch Powell was a Conservative Party Member of Parliament, most famous for his anti-immigration speech, the "Rivers of Blood" in 1968.
Frankie Abbott was boasting about fighting Jackie Pallo at his youth club. Jackie Pallo was an English professional wrestler and actor during the 1960's and 1970's.