Born on the Isle of Mull in the Inner Hebrides in Scotland, he attended school in Oban, followed by the University of Edinburgh and Moray House School of Education.
By 2000 he had become Head of Programmes which gave him responsibility for production and commissioning of all BBC Scotland output.
[1][2] He was appointed Controller of BBC Scotland in April 2004.
[3] His 2012 report into Newsnight (following the programme wrongly accusing Lord McAlpine of abusing care-home boys) led to widespread changes in editorial policy.
[4] MacQuarrie was later commissioned by Director General Tony Hall to investigate Jeremy Clarkson's assault on his Top Gear producer.