The return of Twelvetrees is the only change to the back line that started against Bath three weeks ago.
However, the pack will have a new look. In addition to Hamilton returning in the second row, Huia Edmonds and Shaun Knight come in at hooker and tight head prop respectively.
And the back row will have an experienced feel to it, as Andy Hazell and Peter Buxton start on the flanks.
With just five rounds left in the Aviva Premiership, every game is significant now and Davies is pleased that his side are in the play off picture.
"It's very open, and there's everything to play for. We're fifth at the moment so we're in a position where, if we play well in the next five games, we can finish in the top four.
"We're pleased that we've got that opportunity and we're going to give it our best shot. We've used the last two weeks wisely to prepare, and have really taken things up a level in training this week."
London Welsh may come to Kingsholm at the foot of the table, having suffered a points deduction, but Gloucester are reading nothing into the standings.
"It'll be a big test on Saturday. London Welsh have been extremely competitive all year, they've caught some sides out.
"They bring a real physicality, the contact area will be a real battle and, if you don't get it right, you can come off second best.
"They'll be a bit frustrated with all that's happened recently, and it'll be backs to the wall as far as they're concerned. They'll come out with everything to prove. It's a tough time to play them, a real challenge."
Rob Cook; Charlie Sharples, Mike Tindall, Billy Twelvetrees, Jonny May; Freddie Burns, Dan Robson; Nick Wood, Huia Edmonds, Shaun Knight; Jim Hamilton (capt), Will James; Peter Buxton; Andy Hazell, Sione Kalamafoni
Koree Britton, Yann Thomas, Dario Chistolini, Tom Savage, Akapusi Qera, Dave Lewis, Henry Trinder, Martyn Thomas