"Old Siam, Sir" is a hard rock single from Wings' 1979 album, Back to the Egg. It was the A-side of the UK version of the single, reaching No. 35. The B-side in the UK was also a track from the album, "Spin it On". "Old Siam, Sir" was also the B-side of the US single "Arrow Through Me".
Wings drummer Steve Holly, while playing keyboards during a studio session, developed a chord sequence that was eventually used in the instrumental section of the song.Paul McCartney and guitarist Denny Laine later recorded an instrumental demo for the song called "Super Big Heatwave".