Horstmann has played for England at Sevens

The number eight signed a three-year deal at Harlequins last year, but was surplus to requirements when Quins were relegated from the Zurich Premiership.

Warriors boss John Brain believes the 23-year-old, who also plays blind-side flanker, has a big future in the game.

"He was seen as the heir apparent to Tony Diprose - we think he has a lot to offer," said Brain, director of rugby.

"He's athletic, quick, strong, aggressive and fits the profile of the player we are looking for.

"He's been very frustrated at his lack of opportunities at Quins but we believe that he is a player who has a very big future in the Premiership."