Early and late goals saw Slimbridge return from Hereford with all three points, marking their second League win on the bounce. After conceding an early opener to the hosts, the Swans responded quickly through Theo Clayson, and then deservedly nicked the points in the final minute of the ninety through Shiyak Sutherland's header.
The home side made a positive start and were ahead as early as the third minute - Cam Keetch lofted a ball into the Slimbridge box, and Dan Stoneman was left in acres of space to nod the ball past Olly Phillips and put Westfields into the lead.
The lead only lasted until the seventh minute however - Jacob Rodgers and Shikak Sutherland were already looking dangerous down the Swans' left flank, and it was Sutherland's ball across goal that was converted from a couple of yards out by Theo Clayson for the equaliser.
After Phillips had tipped a good effort from Stoneman over the bar as Westfield applied pressure, Slimbridge nearly nicked a second when Sutherlands cross from an identical position to the goal saw Clayson thwarted by a tackle as he sought to convert another dangerous cross.
Momentum then swung to Slimbridge, with Charlie Hitchings just off target with a header from Ben Hands' corner, further efforts from Sutherland, and an audacious attempt from the centre circle from Will Hawes, who saw his effort beat Westfields Keeper Shay Sterry, but drifted wide of the goal. However, Half Time saw the sides level.
With an hour on the clock, Slimbridge had a huge let off - a Westfields shot rebounded off the post, and Hitchings put in a superb block to deny the follow up attempt.
As the game entered the final stages, the sides exchanged chances - Keetch was off target following a corner for Westfields, and Toby Soule's long range effort for the Swans was just wide following a bad clearance to him with four minutes remaining.
In the end, it was a beautifully worked Free Kick that won the game for the Swans in the 89th minute.
Jonty Welch's lofted ball was met at the back post by Hitchings, and his header across the Westfield goal was guided into the net by the head of Sutherland, to send the away players and fans into raptures.
Referee Dan Ellis played an additional ten minutes of stoppage time, but the Swans held firm to clinch the points.
Slimbridge turn their attention to the FA Cup on Saturday, when they travel to Wallingford and Crowmarch for a Preliminary Round Tie.
A coach is leaving Thornhill Park at 11am, and there are still a few spaces available at £10 per person.
Team: Phillips, Evans, Rodgers, Hands, Dennis, Hitchings, Clayson, Welch, Hawes (Harper 63), Soule (Mills 90), Sutherland
Goals: Clayson 7, Sutherland 89
Supporters Club Man of the Match: Jacob Rodgers