As a result of his lack of funding, Gunn wouldn't race competitively in 2014, but would return in 2015 by taking part in the Aston Martin Evolution Academy.

[7] In 2019, Gunn secured his first full-time FIA World Endurance Championship ride with Aston Martin Racing's GTE Am class entry, driving alongside Paul Dalla Lana and Darren Turner.

[10] Following the 12 Hours of Sebring, Gunn was confirmed as the full-season partner for Roman de Angelis, with team boss Ian James set to step back to the series' endurance events at Watkins Glen and Road Atlanta.

[14] After a difficult start to the season, featuring retirements at both Daytona and Sebring, the duo scored class victories at Long Beach and Watkins Glen, rebounding to finish fourth in the GTD Pro championship.

[18] One of those conflicting dates included the round at NOLA Motorsports Park, during which Gunn was conducting simulator work with the Mercedes-AMG Formula One team.