Billy Vunipola will miss the entire Six Nations even though the fractured arm that he suffered last weekend does not require surgery, with England head coach Eddie Jones confirming that he does not expect to have the No 8 back before the end of the championship.

The Saracens back-row suffered a fractured forearm in last Saturday’s 15-15 draw with Ospreys in what was only his second appearance since returning from a four-month knee injury, and the injury means that the England international will have missed the best part of a year once he eventually returns, following separate injuries to his shoulder and knee in 2017.

With Wasps’ Nathan Hughes also injured, Jones finds himself short of options when it comes to ball-carrying back-rows and as a result, the Australian named Bath’s Zach Mercer in the squad for the first time after serving a “shorter than planned” apprenticeship over the last six months. Hughes could yet return in time for the final three games against Scotland, France and Ireland should he recover from the knee injury that he suffered last month.

“Nathan Hughes [will be back] halfway through possibly,” Jones said after naming a 35-man squad for the opening game against Italy. “He's probably rehabbing a little bit slower than we first thought, [but] I don't think we'll see Billy."

Exeter’s Sam Simmonds is likely to start at No 8 in Rome as a result, but Mercer will certainly be in the mix should he impress Jones during the week-long training camp in Portugal that begins this Sunday.

England Six Nations squad Show all 36 1 /36 England Six Nations squad England Six Nations squad Forwards: Jack Clifford Back row (Harlequins) Getty England Six Nations squad Dan Cole Tighthead prop (Leicester Tigers) Getty England Six Nations squad Luke Cowan-Dickie Hooker (Exeter Chiefs) Getty England Six Nations squad Tom Curry Flanker (Sale Sharks) Getty England Six Nations squad Ben Earl Flanker (Saracens) Getty England Six Nations squad Ellis Genge Loosehead prop (Leicester Tigers) Getty England Six Nations squad Jamie George Hooker (Saracens) Getty England Six Nations squad Nathan Hughes No 8 (Wasps) Getty England Six Nations squad Maro Itoje Lock/back-row (Saracens) Getty England Six Nations squad George Kruis Lock (Saracens) Getty England Six Nations squad Joe Launchbury Lock (Wasps) Getty England Six Nations squad Courtney Lawes Lock/back-row (Northampton Saints) Getty England Six Nations squad Ben Moon Loosehead prop (Exeter Chiefs) Getty England Six Nations squad Brad Shields Back-row (Wasps) Getty England Six Nations squad Kyle Sinckler Tighthead prop (Harlequins) Getty England Six Nations squad Jack Singleton Hooker (Worcester Warriors) England Six Nations squad Billy Vunipola No 8 (Saracnes) Getty England Six Nations squad Mako Vunipola Loosehead prop (Saracens) England Six Nations squad Harry Williams Tighthead prop (Exeter Chiefs) England Six Nations squad Mark Wilson Back-row (Newcastle Falcons) Getty England Six Nations squad Backs: Chris Ashton Wing/Full-back (Sale Sharks) England Six Nations squad Mike Brown Full-back/wing (Harlequiins) England Six Nations squad Joe Cokanasiga Wing (Bath) England Six Nations squad Elliot Daly Centre/Wing/Full-back (Wasps) England Six Nations squad Ollie Devoto Centre (Exeter Chiefs) England Six Nations squad Owen Farrell Fly-half/Centre (Saracens) Getty England Six Nations squad George Ford Fly-half (Leicester Tigers) Getty England Six Nations squad Jonathan Joseph Centre (Bath) Getty England Six Nations squad Jonny May Wing (Leicester Tigers) Getty England Six Nations squad Jack Nowell Centre/Wing/Full-back (Exeter Chiefs) Getty England Six Nations squad Dan Robson Scrum-half (Wasps) Getty England Six Nations squad Henry Slade Centre/Full-back (Exeter Chiefs) Getty England Six Nations squad Ben Te'o Centre (Worcester Warriors) Getty England Six Nations squad Ollie Thorley Wing (Gloucester) Getty England Six Nations squad Manu Tuilagi Centre (Leicester Tigers) Getty England Six Nations squad Ben Youngs Scrum-half (Leicester Tigers) Getty

"The situation means he's [Mercer’s] got a shorter apprenticeship than was first envisaged,” Jones added. “He's now fully available for selection, he's done well for Bath, I've been really impressed by his work-rate off the ball. There's a certain hardness about his game.

“He's always been one of those gifted boys but now he's doing the tough things. I've been really impressed and he could certainly get an opportunity during the Six Nations.”

Jones also confirmed that both James Haskell and Joe Marler will be considered for selection once their respective bans expire after the second match against Wales, with the return of the latter very much needed after Bath’s Beno Obano became the fourth loosehead prop to become unavailable after picking up an injury – joining Marler, Matt Mullan and Ellis Genge in missing out.

Beno Obano suffered a knee injury and missed out on the England squad (Getty)

As a result, Harlequins’ Lewis Boyce joins Exeter’s Alec Hepburn in receiving their first call-ups, with one of them likely to deputise for Mako Vunipola against Italy in little over two weeks’ time.

"Loosehead has been difficult,” he said. “We've lost Marler through his suspension, Genge, Mullan, the rapper (Beno Obano), so he's gone but he might be back during the Six Nations at some stage. So it's given a guy like (Alec) Hepburn, who has been a good performer for his club, a young prop who went on the Saxons tour two years ago, so again a great opportunity for him."

There’s no room either for Leicester’s fit-again Manu Tuilagi, despite the centre returning to action last month and putting together a string of performances following a horrendous run of injuries. Jones would not rule out of possibility of calling Tuilagi up at some point during the Six Nations, but, for now, he wants him to concentrate on finding his form at Welford Road before thinking of an international return.

Jones said: "I'd like to see him get fit. I think Leicester would like to see him get fit and that's what we're hoping is going to happen. If he does that, then he'll be a chance to get selected.