"Leon has great feet and a great turn of foot and also an accomplished finisher and will be a good addition to our squad.”
"We would like to place on record our thanks to Handsworth FC for helping us get this one over the line so Leon will be available for Saturday's game."
On the move, Howarth said: "I'm blessed to have an opportunity to play for a club like Gainsborough.
"I've heard all great things about this club and I want to bring my abilities along with me to ensure this team goes forward. I hope my time at this club brings joy to myself and everyone associated with the club. I can't wait to get going."