England determine who can cope with extreme demands

The 45-strong squad returns from Colorado this weekend following a fortnight of gruelling sessions – sometimes totalling four a day – conducted at altitude and amid temperatures scaling 32C.

Only two days of kayaking, fishing and golf have offered respite from the arduous task of preparing for England 2015, which opens against Fiji on September 18.

Backs coach Farrell refuses to be drawn into any mind games with Group A rivals Wales, who have been trumpeting the value of their camps in Switzerland and Qatar, instead focusing on the efforts of his own players.

“The desire of the squad to get through one gruelling session together was absolutely awe-inspiring from a coach’s point of view,” Farrell said.

“They have been digging in together and suffering together and will come out a better team because of that.

“You get to know the players better because they’ve had to dig deep.

“We’re not flogging them, but asking them questions about their ability to execute skills wise while under pressure and in extreme conditions. We’ve seen who can cope with that and who can’t.

“The players couldn’t have given any more. In fact we had to hold back [yesterday] because this week has been pretty brutal.

“Everyone says they’ve had the best pre-season of all time, but we’re unbelievably happy with the plan and how it’s going.

“The boys are 100 per cent committed to the cause. The pain and excitement they have been going through together has been plain to see.”

Farrell insists Bath’s rugby league convert Sam Burgess remains a contender for the final 31-man World Cup squad after acquitting himself well during inter-squad matches at inside centre.

League convert Burgess is only being considered in the midfield for the upcoming World Cup, despite producing his best rugby as a blindside flanker for Bath last season. England’s high-altitude training camp in Colorado has given the management the chance to assess him in direct competition with his rivals for the four centre berths in the final 31-man squad, which is announced on August 31. Backs coach Farrell insists the 26-year-old, who swapped league for union last October, remains in contention for World Cup selection.

“We picked him in our training group as a 12 so we clearly believe he can play there,” Farrell said.

“He’s given a very good account of himself so far this week. He’s looked very comfortable in the centres.

“We’re more into the rugby element of training now and he’s showed up well.

“The competition is fierce in that position, but Sam’s in the mix and doing very well.

“If you look back at his league days, he’s played in many different positions from front row to loose forward and those positions are a mile apart.

“What you find with a good footballer with a feel for the game is that they’re able to adapt and play many different positions. Sam is one of those.

“Everyone is trying to give themselves a fighting chance of getting into the warm-up games and play the best they can, and Sam is no different to anyone else.”

England return from their two-week camp in Denver this weekend with their first World Cup warm-up match against France at Twickenham looming on August 15.