After Dad's Army ended, Dunn capitalised on his skill in playing elderly character roles by playing the lead character Charlie Quick, in the slapstick children's TV series Grandad, from 1979 to 1984 (he played the caretaker at a village hall, and sang the lyrics in the theme). He had previously had a number one hit single with the song "Grandad" on his fifty-first birthday in January 1971, accompanied by a children's choir. The song was written by Bassist Herbie Flowers. He performed the song four times on Top of the Pops. The B-side of "Grandad", "I Play The Spoons", also received considerable airplay. After the cancellation of Grandad in 1984, he disappeared from the screen, and retired to Portugal. Following the success of the "Grandad" record, Dunn released several other singles.