Sinfield, rugby director at the Rugby Football League (RFL), has outlined his responsibilities with the Test sides in the wake of criticism following Great Britain’s dismal southern-hemisphere tour.
The Lions – in their first action for 12 years – were beaten 2-0 in a Test series against New Zealand and also lost to Tonga and Papua New Guinea.
Sinfield – a former England captain – was with the squad for the second half of their month away and made no effort to hide his dismay at the outcome.
He said: “I am hugely disappointed with the tour – we underperformed and under-achieved.
“Clearly there are some things we could have done better.
“That has been my role every time I have been out there with the senior team, whether it be England or GB.
“It has been with a view to coming back with some improvements and recommendations from a performance perspective, to make sure we improve each year and improve each camp that the men are together.
“Contrary to what people may think about selection, I play no part in that whatsoever. My job is to try and enhance all our programmes and make them better.”
The inquest now under way into the tour is not a panic move in response to poor results and performances, Sinfield said.
He added: “It has been well-documented there will be a full review. That was taking place anyway, because we do that after every tour or Test series and it is really important to try and improve all the programmes.”
Wayne Bennett’s contract as England and Great Britain coach has now expired.
He was assisted with the Lions by London Broncos’ Danny Ward and Ian Watson who guided Salford Red Devils to last season’s Betfred Super League Grand Final.
Sinfield, who is also rugby director at Leeds Rhinos, insisted: “We have a head coach who picks the team.
“And we had two very good assistants with him who play a part in selection.
“I think it’s really important it is the coaches, otherwise what’s the point of them being there?
“Their role is to coach the team and they get to select it.
“My role within that is to review all aspects of performance, which does include selection after the event.
“It is easy with hindsight.”
Sinfield’s former Leeds Rhinos team-mate, Jamie Peacock, who was team manager on the tour, has also come in for criticism.
But Sinfield stressed: “It is probably thought that he plays a role in team selection, but that’s not true at all. He does a fantastic job as team manager and he’s probably the best team manager we’ve ever had.
“I think all our staff have done a very good job; it’s just performances on the field and the results paint a very different picture.
“We will work through that in the report and we’ll try and make improvements in every area so that next time there’s a GB tour or an England get-together we are better.”
Meanwhile, Leeds Rhinos’ traditional fixture against Hunslet will take place at the South Leeds Stadium on Friday, January 31, kick-off 7.45pm.
Admission to match will cost £10 for adults and £5 for concessions with under-16s going free but Hunslet are inviting spectators to make a further voluntary donation towards the continued running of the club as a supporters-run model.
Leeds have already announced pre-season fixtures at home to Wakefield Trinity on Boxing Day and Bradford Bulls on January 12.
They will then play at Featherstone Rovers on January 24 and travel to Newcastle Thunder on January 26.