Malcolm enjoyed "cowboy movies" and cartoons. His parents were from Trinidad, but Malcolm was born in Britain. His family were members of the Church of England. His mother worked at a newsagent's shop and his father worked on the buses. His favourite toy was a cowboy gonk.
When Susan picked Malcolm up from his mother's newsagent's on 30 March 1963, a soldier called him a "golliwog" and said that he should "go back where 'e came from". Susan complained to a sergeant, who was unsympathetic.
Three days later, when London was brought to a standstill by the Cold, Susan, Gillian Roberts and John Brent encountered Malcolm while taking shelter from the Cold in a Wimpy Bar. Mr and Mrs Haigh, Dolly and Zack were also taking refuge in the restaurant. When Susan, Gillian and John decided to go, Mrs Haigh, who had become deranged by the crisis, held Malcolm at knife-point and threatened to sacrifice him to God. Dolly and Zack saved Malcolm, and the young people left the Haighs at the Wimpy Bar.
Susan led the group to the junkyard in Totters Lane, where her grandfather was communicating with the Cold (Dolly was killed en route). The Doctor was prepared to let the Cold destroy the human race, saying, "Have you ever seen anything as perfect as a snowflake?" Susan replied, "Yes," and pointed to Malcolm. The Doctor was still unconvinced until Malcolm offered him his cowboy gonk. Struck by the absurdity and creativity of the toy, the Doctor agreed to help move the Cold to Pluto.
However, the Cold did not wish to comply. The Doctor used a lash-up of machinery to trap the Cold, and Malcolm provided the "motive power". The Doctor suggested that Malcolm may have been born in a caul, as he had a large degree of the power which the Doctor required.