The incident happened on the third lap of the race at Snugborough between Braddan and Union Mills, causing a red flag stoppage.
The tragic news was confirmed by his wife on Mathison’s Twitter account on Monday afternoon in a post that read: “Not something I ever wanted to write but here we go.....Daley, as Daisy says, is now sleeping with the fairies. That’s all I can bring myself to say right now. The last image I saw of my husband, was of a man so happy with life and so proud of his racing.”
Mr Mathison (27), from Stockton-on-Tees, was competing for the Penz13.com Racing team on a 1000cc BMW machine.
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He was a former winner of the Ultra Lightweight race at the Ulster Grand Prix in 2014 and was also a three-time podium finisher at the TT in the Zero race, earning a runner-up finish last year following two third place results in 2016 and 2017.