A British jazz drummer.

Throughout his career he played in a wide range of musical contexts. Having gained his reputation working with the post-war big bands of Joe Loss and Jack Parnell playing firmly in the tradition of Gene Krupa, he went on to become one of Europe's foremost bebop drummers and possibly the most sought-after jazz drummer on the British jazz scene of the mid-1950s and 1960s. He was a key member of the free form quintet of Joe Harriott in the early 1960s and, alongside a long-running on/off musical association with Harriott, he played and recorded with virtually every key figure of 1950s and 1960s British jazz, including Ronnie Scott, Dick Morrissey, Harold McNair, Don Rendell, Victor Feldman and George Chisholm, to name but a few. Later in his career he worked with Alexis Korner and had a spell with Ginger Baker's Air Force, the leader of the band being one of Seamen's foremost disciples.

He also played with myriad visiting American musicians, backing performers such as Stan Getz, Roland Kirk and Freddie Hubbard, often at London's Ronnie Scott Club.

Seamen was almost as well known for his dishevelled lifestyle as for his drumming, battling both heroin addiction and alcoholism until his death.