It extended Harvest’s unbeaten run to five games while Andover New Streets and Clanfield jumped above Locks, who are now fourth.
Locks had taken the lead shortly into the second half at Front Lawn when keeper Jordan Camburn allowed a Joe Roberts shot to slither through his grasp.
A succession of subs played their part in Harvest’s comeback.
Jack Lawton, who had replaced the injured Jordan Lloyd in the first half, levelled on 74 minutes with a shot from the edge of the 18-yard box that went through a crowd of bodies.
Issy Bangura, on as a second half sub, then went clean through on goal. But after his shot had been saved by Max Hoile, the ball hit a Locks defender on the head and rebounded into the net.
A third Harvest sub, Harry Byrne, won the penalty from which Logan Vickers made it 3-1 on 82 minutes.
It was a first HPL appearance for Byrne since suffering a broken leg early in the 2021/22 season, having been playing for the club’s reserve team since his comeback.
Banguara completed Harvest’s best result of their entire Hampshire League career with a shot into the top corner.
It was the first time Locks had conceded four in a league game since the opening game of 2020/21, when they lost 4-3 at Fleetlands.
Harvest boss Wayne Lawton said: ‘It was probably the best we’ve played all season.
‘Locks are a good side, you don’t get to second in the league and the League Cup final without being a good side. But we fully deserved the result, we controlled the game throughout.
‘On our day, we’re definitely a match for teams in this league. We’re just not consistent enough, that’s our problem.’
Harvest are now up to fifth in their maiden HPL Senior Division campaign, though Denmead are just two points behind with five games in hand.
The two clubs who share Front Lawn on a Saturday afternoon meet there next Saturday in what is Denmead’s home game.
A lone Ryan Chandler goal gave Denmead all three points when the teams first met in Senior action last August.
1. Action from Harvest's 4-1 win at home to Locks Heath (red and black kit) in the Hampshire Premier League
Action from Harvest's 4-1 win at home to Locks Heath (red and black kit) in the Hampshire Premier League. Picture: Keith Woodland (180321-1520) Photo: Keith Woodland
2. Action from Harvest's 4-1 win at home to Locks Heath (red and black kit) in the Hampshire Premier League
Action from Harvest's 4-1 win at home to Locks Heath (red and black kit) in the Hampshire Premier League. Picture: Keith Woodland (180321-1508) Photo: Keith Woodland
3. Action from Harvest's 4-1 win at home to Locks Heath (red and black kit) in the Hampshire Premier League
Action from Harvest's 4-1 win at home to Locks Heath (red and black kit) in the Hampshire Premier League. Picture: Keith Woodland (180321-1427) Photo: Keith Woodland
4. Action from Harvest's 4-1 win at home to Locks Heath (red and black kit) in the Hampshire Premier League
Action from Harvest's 4-1 win at home to Locks Heath (red and black kit) in the Hampshire Premier League. Picture: Keith Woodland (180321-1409) Photo: Keith Woodland