Hartley has a knee injury and misses the opening game with Grand Slam champions Ireland on February 2 and is likely to sit out the next game with France. He is not joining the rest of the squad on their Portugal training camp and also out injured are Jonathan Joseph and Chris Robshaw while Danny Care has lost out to Dan Robson for the third scrum-half place.
Jones said: “Unfortunately, Dylan won’t be available for the Ireland game so we won’t take him to Portugal but we are hopeful he will be back later in the series. Owen will be captain by himself and he will certainly have great support from a number of senior players.
“He is an important player for us, he has played over 50 Tests. Billy has had a dreadful run of injuries, he’s also played two good games for Saracens and we’re delighted to have him back in the squad.
Thorley won the World Rugby U20 Championship with England in 2016, and on his inclusion Jones said: “He is a big strong lad, he runs hard, he has got good pace and good strength, has improved his skill and understanding of the game and deserves his opportunity.
“Both Jack and Ollie (Devoto) were important members for us in 2016 and 2017, both have had difficult times with injuries and both have now come back with their clubs and played really well. Ollie is a good, strong inside centre and Jack can play six, seven or No 8.”
Sign up to our mailing list here and we’ll keep you up to the minute with weekly updates from the world of rugby.