Sarries forward coach has been touted as a possible replacement for Paul Gustard, who has joined Harlequins

Saracens would be reluctant to lose Alex Sanderson to England after Mark McCall revealed he is seen as his eventual successor as the club’s director of rugby.

Eddie Jones is looking for a new defensive mastermind after Paul Gustard agreed to join Harlequins as head coach upon completion of next month’s tour to South Africa.

Sanderson, who in 2005 was forced to retire as a 25-year-old due to a back injury, replaced Gustard at Allianz Park and has also been touted to fill his shoes with England.

McCall, however, insists Saracens are eager to retain the services of a coach they rate very highly.

“Not really no,” McCall said when asked if he would be happy for Sanderson to join Jones’ backroom staff.

“It’ll be Alex’s decision, that’s for sure. Alex contributes so much to this club that it’s hard for us to say really. He’s not just a defence coach, he’s way more than that. He’s a brilliant coach.

“But he also understands that he’s young - he started coaching when he was 27. He knows he’s in a great place and a great job at the moment and he’s in no rush as far as I can see.

“He should be the director of rugby at this club at some point. And I hope that’s what he wants to do.

“As a club we want to promote from within when it’s possible, that’s for sure. If I’m told to leave or leave, then Alex should be the only candidate for the job.

“Paul worked with us for six years and was brilliant here. He’s our friend first and foremost, and also a great coach.”

Billy Vunipola is expected to start Saturday’s Aviva Premiership final against Exeter at Twickenham as Saracens continue to monitor his tight hamstring.

The England number eight lasted only the first half of the play-off victory over Wasps in his latest comeback from injury but McCall insists he should be given the all clear.

Wales full-back Liam Williams could return from the shoulder issue sustained against Gloucester on May 5 but his outlook to make the showpiece against the Premiership champions is less positive.

“Billy did a little bit of training this morning (Tuesday) and will train again on Thursday,” McCall said.

“We expect him to be available to play. We’ve just got to be sensible with him. Hopefully he will be OK.

“Liam Williams is touch and go and we’ll make a call on him on Thursday. Everyone else who played last weekend we hope to have available.”

Vunipola’s fitness has repercussions for England as the powerful back row has been named in Jones’ squad bound for South Africa next month.

The 25-year-old returned from a fractured arm against London Irish earlier this month only to be struck by the hamstring complaint that has limited his game time ahead of the three-Test series against the Springboks.

“If his hamstring is OK and everything is OK post final, then it would be a good thing for him to go on the tour,” McCall said.

“Clearly if he’s carrying something then it wouldn’t be the best for him to go on a three-week tour.”