Coltrane started his career appearing alongside Hugh Laurie, Stephen Fry, and Emma Thompson in the sketch series Alfresco.

In 1987, he starred in the BBC miniseries Tutti Frutti with Thompson, for which he received his first British Academy Television Award for Best Actor nomination.

[1] In 2016, he starred in the four-part Channel 4 series National Treasure alongside Julie Walters, a role for which he received a British Academy Television Award nomination.

Though he later described his experiences there as deeply unhappy, he played for the rugby First XV, was head of the school's debating society, and won prizes for his art.

[7] Coltrane later called for private schools to be banned and used to be known as "Red Robbie", rebelling against his conservative upbringing through involvement with Amnesty International, Greenpeace, the Labour Party, and the Campaign for Nuclear Disarmament.

[14][15]Coltrane moved into roles in films such as Flash Gordon (1980), Death Watch (1980), Balham, Gateway to the South (1981), Scrubbers (1983), Krull (1983), The Supergrass (1985), Defence of the Realm (1985), Absolute Beginners (1986), Mona Lisa (1986), and appeared as "Annabelle" in The Fruit Machine (1988).

The same year he starred opposite Jeremy Irons in the television film adaptation of Roald Dahl's children's book Danny, the Champion of the World.

[20] His roles continued in the 1990s with the TV series Cracker (1993–1996, returning in 2006 for a one-off special), in which he starred as forensic psychologist Dr. Edward "Fitz" Fitzgerald.

[22][23] Coltrane also presented a number of documentary programmes for the British ITV network based around his twin passions for travel and transportation.

[1] In August 2007, Coltrane presented a series for ITV called B-Road Britain, in which he travelled from London to Glasgow, stopping in towns and villages along the way.

[27] Coltrane voiced characters in several animated films, including The Tale of Despereaux (2008) and Pixar's Brave (2012), as well as the title roles of Gooby and The Gruffalo (both 2009).

[31] Maureen Ryan of Variety wrote that "Coltrane does a masterful job of depicting every nuance of the character, whose wicked sense of humor masks a startling, and possibly intentional, lack of self-awareness".

There are all sorts of advantages to being part of the United Kingdom and it would be foolish to throw it away immediately" and "I have no time for the nationalists – all they can do is split the vote for home rule and let the Tories in".