Davies has been sidelined by a pectoral injury since the autumn internationals but impressed on club duty with the Scarlets last weekend while Jones missed Wales' win over France with an infected toe.
And Warren Gatland admits it is a huge fillip for his Wales side to have two key players return to the starting line-up at Twickenham
"It's great to have both Jon and Alun Wyn back and available and they come into a very experienced side," he said.
"Jon came through the match well at the weekend and he is ready to go. We were happy with the response and performance against France but we know we will have to raise it another level on Sunday.
"We are really looking forward to going up to Twickenham, England have performed well so far and its set up to be a great game with all to play for."