It’s June, 1970, and Keith Mitchell and Diana Rigg — stars of the Wyndham Theatre’s production of Abelard and Heloise — take a spin along London’s Charing Cross Road. The side-by-side cycle is an 1880 Starley Meteor Sociable, or “honeymoon” bike. Mitchell, an Australian, moved to the United Kingdom where he enjoyed a long career on stage and screen. Rigg continues to perform.