The 22-year-old full-back has just concluded his best season yet as Wealdstone reached the play-offs.
Grant even scored some crucial goals last in the campaign - including in their heartbreaking defeat to Woking.
Now Alan Devonshire has swooped to bring the defender up a level.
His son and chief scout Lee thinks his club have a player with bags of potential.
He told the Magpies website: “Freddie is someone who has plenty of experience for one so young.
“He has been in the National League South for a few years now at the likes of Oxford City, Farnborough and more recently Wealdstone.
“He is a left/back with good energy, a competitive side and he chips in with the odd goal so he will be a player that will be a valuable asset to us moving forward."