He joined the Royal Shakespeare Company in 1984 and his Shakespearean roles included Friar Lawrence in "Romeo and Juliet", Quince in "A Midsummer Night's Dream" and Holofernes in "Love's Labour's Lost". Middlemass also appeared widely in classic plays such as "Rosmersholm", "Heartbreak House" and "You Never Can Tell". Even in his eighties, Frank Middlemass was still performing on stage, notably in "The Importance of Being Earnest" and toured with a one-man show called "Frankly Speaking". In his final years, he made appearances in "Kavanagh QC", "Casualty", "The 10th Kingdom", "Doctors" and "Midsomer Murders". In 2005, "As Time Goes By" returned for two reunion specials, aired in Christmas that year, and this was his final television appearance. Middlemass never married, and for forty years he had a room in the house of his close friend, actor Geoffrey Toone, who died in 2005 after spending some time resident at Denville Hall. "To their general amusement", they were often mistaken to be lovers, but in fact were not. Middlemass died, aged 87, in Northwood, London.