McGlashan began life in the youth team at non-league Tooting & Mincham before moving on as a youngster to Staines Town.
He graduated to the Swans senior set-up in 2006 making a couple of appearances before joining Bracknell Town on a dual registaration in the 2007/08 campaign.
Over the next couple of seaons he spent time with the likes of Kingstonian, Raynes Park Vale and Mertsham before signing for Ashford Town with whom he made his breakthrough.
With the Ash Tree’s he was discovered by a host of Football League clubs with whom he spent multiple trials including Bristol Rovers and Southampton.
In the summer of 2010 he eventually moved up to then-League Two side Aldershot Town on an initial one-year deal.
His professional debut came at age 22 where he came on as a substitute against Watford in the League Cup in August 2010. His first professional goal came in November of that year in a 2-2 draw with Hereford in League Two.
After earning a new deal and making over 60 appearances in his first two seasons with the Shots, he moved on to Cheltenham Town in January 2012 signing a two and a half year deal- just days after taking them on in his last Aldershot game.
He was the first January signing made by the Robins that required a fee, thought to be around £60,000.
His performences helped Cheltenham secure a League Two play-off position and in the semi-final he scored in both legs against Torquay to send the Gloucestershire outfit to Wembley, which they went on to lose 2-0 to Crewe Alexandra.
McGlashan eventually departed Whaddon Road in 2014 moving up to Sky Bet League One side Gillingham who had been chasing the winger since 2012.
He made his debut in League One against MK Dons in August 2014 with his first goal coming in January 2015 in a 3-1 win over Coventry City.
Having spent two years at Priestfield he made the switch to Southend United in League One spending a further two years in the division before evetually heading to Swindon Town in the summer of 2018.
His Swindon debut came in a 3-2 home victory over Macclesfield Town before going on to make a further 27 appearances in all competitions for Swindon.
In March 2019 he made a loan move to Wrexham with no place for the winger in the manager’s plans at the County Ground.
His Wrexham loan will run until the end of the 2018/19 campaign and was the first outfield player brought in by manager Bryan Hughes.
On Loan From Swindon Town