The striker has netted in his past four games since making the Switch from Oadby, including Saturday’s 3-1 victory at Peterborough Northern Star.
Craig Smith had pulled the hosts level before Callum Milne and Ryan Hardy netted in the final 10 minutes to secure victory.
“We had been actively working to bring in a forward who could make a difference,” manager Spencer said.
“Not only has Harry been that forward, not only has he scored four goals in five games, he’s also had a really positive effect on Dan Forbes.
“Dan was playing well, but I felt he needed the right partner with him.”
The Bees have now scored 14 times in their past five games, resulting in three draws and two victories, with Forbes and Wakefield accounting for six of those goals.
“We’ve conceded a few across the last five games as well, but you don’t feel the pressure the same when you’re scoring at the other end,” Spencer added.
“We’ve got a good defence who have played consistently well.
“But when you’re scoring goals it takes some of that pressure off.”
Reflecting on the game, Spencer added: “We scored two late goals to win, but I think the overall scoreline was a fair reflection of the game.
“I thought we dominated the game and had the majority of the ball.
“But if you only lead by one goal you can get caught out, and that’s what happened.”
Elsewhere in the United Counties League Premier Division, Lutterworth Town were beaten 6-2 at highflying Holbeach United.
Just days after beating the Tigers 1-0, it was a different story at Carter’s Park.
Reed Tomlinson scored both Swifts goals.
The results leave Harborough ninth in the Premier Division table with Lutterworth 13th.