Terry Venables, Portsmouth's director of football, made his first visit to the club in three weeks to see Bull take his total for the season to eight with a goal in each half.
The win leapfrogged Wolves above the early-season pacesetters, Barnsley, who could only draw at home to Oxford.
Sheffield United put themselves back in the promotion race with a 3-0 win over Charlton. The Belarussian striker Petr Katchouro grabbed two second-half goals, before Andy Walker made sure of the points.
Around 1,000 protesting Brighton supporters staged a demonstration outside the Goldstone Ground following the Seagulls' 1-0 defeat against Hereford. The demonstration lasted for 20 minutes and ended peacefully, fans having walked out of the match 15 minutes from time.Reuse content