The 20 year old midfielder has come through the Palace youth system but has decided to look for regular first team football at Adams Park.
"He is a very good young professional and very serious about his work,"the boss told the official webiste.
"He's a powerful forward running midfield player with a very good left foot. Lewwis has a great hunger for the game and that's what I'm looking for. I want players to come in, to be hungry and prove a point. He fits the bill."