Since January 2010 McNab has had 279 starts and 21 wins in eventing. He has had 33 starts in jumping.
In 2013, his mount Clifton Pinot was found to have the banned substance reserpine in his system while competing at the Burghley International Horse Trials. He was eliminated from the competition.[3] In 2014, McNab was cleared of the charges after an equine supplement supplier claimed responsibility.[4]
At the Le Lion d'Angers World Championship, in October 2019, McNab was ranked 9th on Halo. He was eliminated when competing in the 2020 event.[5]