An England international, he played for clubs such as Crystal Palace, Arsenal, Newcastle United, Coventry City, Queens Park Rangers, Everton and Watford.
[6] He considered himself a goalkeeper in his early years, but while playing for a youth team called Spring Park Wolves he replaced an injured teammate at left-back, and remained a full-back for the rest of his career.
[8] Sansom was scouted by Arsenal, Queens Park Rangers and Tottenham Hotspur, but went on to join the youth team at Crystal Palace.
[13] Sansom made his Arsenal debut against West Bromwich Albion on 16 August 1980 and was an ever-present for the whole of that season and also the next, and a near-constant figure at left-back for the North London club.
The next two seasons saw a top-five finish in 1982, and a disappointing tenth in 1983 when matters were not improved by semi-final failure in both domestic cups at the hands of Manchester United.
In May 1986, Millwall manager George Graham, a former Arsenal player, was appointed as Howe's long-term replacement, and it was the beginning of a new era of success at Highbury.
[13] The following season, Sansom's relationship with his Arsenal manager Graham soured and he was replaced as captain by fledgling defender Tony Adams, who was just 21.
Sansom transferred to QPR in the summer of 1989 for £300,000 and scored against Arsenal in a 2–0 FA Cup fourth round replay victory at Loftus Road.
[19][20] Sansom made one league appearance for Watford, before he retired from top class football, though he did play on for non-league clubs such as Croydon F.C.
[23] Sansom missed only a handful of England matches between 1980 and 1988; his record of 37 consecutive appearances between May 1984 and April 1987, has only been bettered by Billy Wright and Ron Flowers.
He was occasionally rested in friendly matches so that coaches Ron Greenwood and then Bobby Robson could check on potential replacements Derek Statham, Alan Kennedy, Nick Pickering and Stuart Pearce in the event of losing Sansom either through serious injury or chronic loss of form.
[23] That summer, Sansom was Robson's first-choice left-back for the European Championships, but England lost all three of their group games, starting with a surprise 1–0 defeat to the Republic of Ireland in their first ever finals match, having qualified under the management of Englishman and World Cup winner Jack Charlton.
[23] Sansom made an error for the only goal of the game, toeing an attempted clearance high into the air and putting pressure on his fellow defenders, from which John Aldridge won a header for Ray Houghton to nod the ball past Peter Shilton.
[citation needed] On 7 February 2014, Sansom appeared at court in Bromley, charged with assault following an alleged incident at his former partner's property.
[26] In 2016, Sansom was a guest on "Thursday Focus" on Manchester United's in-house TV channel, MUTV, discussing his career and his life after football.