The Headmaster was played by Andrew MacTavish.

Mr. MacTavish is a well-known figure in High Wycombe the location of the real Kings School.

In fact he was actually a boarder at the Royal Grammar School High Wycombe where the series was filmed from 1948 to 1956. He later returned to the RGS and took up teaching there. Later on in his career he became Headmaster at the John Hampden Grammar School, where he was affectionately known as "Big Mac", a job that he held for 17 years until his retirement in 2000.

Earlier in 2003 he came out of retirement to stand in as Headmaster at the Wycombe High School after the previous Headmistress left suddenly. This was a totally new experience for him being in charge of an all girls' school. Apparently he earned the nickname Head mistress from his colleagues.

Immediately after retiring again he stepped into the shoes of Headmaster at the fictional Kings School. He must of felt his school life had gone full circle.

He is still on the board of governors at the Royal Grammar School.