Having trailed 21-6 at one point, three tries on the bounce looked to have the visitors on the comeback trail, only for Aled Thomas to recapture the lead with a penalty eight minutes from the end.
But it was to be the Wanderers’ night and one final charge yielded a penalty against the head at the scrum, Mallinder stepping up and thumping it straight down the middle with the final act of the game.
The Wanderers’ evening started with a spell of defence and while Gloucester struggled to find a way through, a penalty went to the corner and Billy Burns grounded beside the posts.
Having withstood a substantial period of Wanderers pressure, Gloucester would score next, too. Shane Monahan scooped up a kick to cut free out of defence and his territorial gain would eventually lead to Will Safe sliding into the corner.
Things weren’t clicking for the men in black, green and gold, but in keeping the pressure on, Will Hooley was able to reward their efforts just after the quarter with a pair of well struck penalties.
While Steph Reynolds burnt onto a kick through for home try number three, play quickly shifted back to the other end of the field and after Collins’ lovely offload released Stephenson, Hooley’s cross kick provided Jamie Elliott with an easy finish.
Hooley converted from tight on the left touchline to cut the gap further and the Wanderers would remain on the front foot as the game got back underway.
The Cherry and Whites still needed some breaking down though and it was a quick tap from Alex Day that did the trick, the scrum-half getting back on the ball to stretch over after some muscular work from the forwards.
By now, possession was almost solely theirs and while Hooley narrowly missed a chance to capture the lead from the tee, Gloucester weren’t getting off that easy.
Reece Marshall rode a huge hit well and the ball was recycled for Hooley to dink over the top, Collins pulled back from the ball at the cost of a penalty try.
Surrendering the lead for the first time seemed to spring Gloucester back to life, but like their visitors before them they would have to work hard for what would be their bonus point try just after the hour.
Lloyd Evans was the man to cross and though Aled Thomas would miss the conversion, a more straightforward penalty allowed Gloucester’s skipper to recapture the lead eight minutes from time.
The Wandies regathered and having earned the territory with a penalty upfield, they then pinched another against the head at the scrum. Some 40 metres out and on the angle, Mallinder did the rest.
6mins GLOS Try & Con Burns 7-0
15mins GLOS Try Safe Con Burns 14-0
23mins WAND Pen Hooley 14-3
26mins WAND Pen Hooley 14-6
32mins GLOS Try Reynolds Con Burns 21-6
36mins WAND Try Elliott Con Hooley 21-13
HALF-TIME GLOS 21 WAND 13
48mins WAND Try A Day Con Hooley 21-20
55mins WAND Try Penalty Con Hooley 21-27
64mins GLOS Try Evans 26-27
72mins GLOS Pen Thomas 29-27
80mins WAND Pen Mallinder 29-30
FULL-TIME GLOS 29 WAND 30
GLOUCESTER Thomas (capt); Purdy, Isaacs, Meakes, Monahan; Burns, Braley; Gibbons, Lutui, Knight, Stooke, Hicks, Voss, Luxton, Safe
Reps: Cole, Goodrick-Clarke, Clarey, Batley, Thomas, Bassett, Evans, Reynolds
WANDERERS Collins; Elliott, Waldouck (capt), Stephenson, Packman; Hooley, A Day; E Waller, Marshall, Denman, Woolford, Craig, Dolan, Harrison, Fisher
Reps: Fish, Hobbs-Awoyemi, Parkins, Onojaife, Ludlam, Robinson, Mallinder, Hutchinson
REFEREE Philip Davies