The Three Bells is a play on the famous Ten Bells Pub near Spiatfields in East London. The old docklands of that region have since been transformed into new living and working space. The pub is still in use. It has association with the Jack the Ripper tale, too.
The British Invasion brought not only music, but fashion, to the world. It was a time of Twiggy cuts for women and long hair for men, ladies' mini skirts and go go boots, wildly striped trousers and Cuban heeled Beatle inspired footwear for blokes, and a modernistic mixture of color and patterns. For a time, London (and England) truly were the center of the universe.
Inspector Watson's name is a play on Sherlock Holmes' venerable assistant, Watson. A portrait of Holmes is prominently displayed in his office.
Per the title, someone who does not know the answer to a question might reply with this common saying: I haven't the foggiest notion.
Along with Big Ben and St. Paul's Cathedral, Tower Bridge is one of London's most recognizable landmarks.