The 21-year-old has won plenty of admirers during his time with the Brewers, having signed for their Academy after impressive spells at Redditch United and Halesowen Town.
Penning a first professional deal there around a year ago, Sam enjoyed a fine spell out on loan last season in the National League North with Brackley Town.
Whilst there, a string of commanding displays and clean sheets not only helped Brackley secure their north league status, but also won him the Vanarama player of the month award for April.
He earned recognition from his own colleagues, too, with the management and players their hailing him as their player of the season.
Hornby, equipped with key knowledge of the division, has signed for Harriers on a season-long loan.