[1] By the late 1940s, he was working in the visual and sound editorial departments of Shepperton Studios for films produced by Alexander Korda,[2] such as The Third Man (1949) and The Wooden Horse (1950).

Following the release of Moonraker, Glen was promoted to the rank of official director of the series;[4] he went on to direct all five Bond films of the 1980s.

The films are: After Bond, Glen continued to direct, with credits including Christopher Columbus: The Discovery (1992) and The Point Men (2001).

As editor of Moonraker, Glen was responsible for creating the "double-taking pigeon", an editing trick that makes it appear as if a bird in St Mark's Square in Venice cannot believe its eyes when Bond's (Roger Moore) gondola transforms into a hovercraft.

In addition, all of Glen's Bond films feature a character who dies by falling from a height, in a sequence commonly accompanied by the same "male scream" sound effect.