The midfielder was recently released by Gainsborough Trinity, having started his career at Doncaster Rovers making 63 appearances.
He could make his debut against Stamford on Saturday.
Manager Dave Smith said: "I have been looking for the last couple of weeks to add to my options in central midfield.
Harry was the one that I really wanted to bring in, so I'm very pleased to get this deal done. As always, thanks to the Board for their excellent support. He is a player of great pedigree, with Football League experience, and fits in to the way that I want us to play.
The competition for places will now be fierce. Harry has come here to help us kick on and will prove to be an excellent addition for the Club.
I'm sure that all our loyal supporters will enjoy watching him play in a Clee Town shirt - UP THE OWLS!"
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