Following retirement, he returned to Brentford as a youth team coach before running the Arsenal soccer school in Oman.
Marshall started his playing career at Arsenal and broke into their first team at the age of 19, winning five Scotland under-21 caps.
[3] He scored his only goal for the Gunners in their 2–0 victory over Newcastle United in March 1996[4] and at the end of that season was voted as Arsenal's Young Player of the Year by the supporters.
[8][9] This meant that Marshall had featured in just three league games in the 1998–99 season (two for Southampton and one for Celtic), had lost all three and had conceded ten goals.
[11] After battling his way back to fitness, he at last gained regular first team football making a total of 94 appearances for the Bees, scoring seven goals.
[17] He spent time living and working in Muscat, in the Sultanate of Oman, running the Arsenal Soccer School.
[18] He worked alongside Paul Lambert at Wycombe Wanderers[19] before accepting the position as U-21 development squad head coach at Premier League side Norwich City in the summer of 2012.
[25] On 6 March 2023, Marshall was once again reunited with Ben Garner at Colchester United after being named as assistant head coach.