The 22-year-old opened the scoring after just a quarter of an hour with the first real chance of the game, dancing along the edge of the 18-yard box before beating Nicholas Bilokapic at his near post. Gullan then added a quickfire second moments later as he converted from Innes Murray’s pass.
Losing two goals in two minutes seemed to spark the Terriers into action and goalkeeper David Mitchell had to be alert to keep out an attempt from Micah Obiero.
It was little surprise when the hosts did find a way back into the game given their sustained pressure, Kian Harratt’s late run helping him beat Mitchell to Jon Russell’s cross to halve the deficit.
Russell nearly added a goal of his own ten minutes before the interval but dragged his effort wide of the post.
On the stroke of half-time Harratt squared the game, drilling home his and Town’s second from Ben Jackson’s cross.
The second half began in the same fashion, Mitchell denying Harratt his hat-trick before Campbell tested Bilokapic.
Hibs retook the lead on 70 minutes, Jack Brydon teeing up Gullan for his and Hibs’ third after a stramash in the box following a corner.
Substitute Josh O’Connor added a fourth when his angled shot sneaked in before Harratt saw a late penalty saved after a handball in the box.