Stuart Lancaster stepped down as England coach three years ago after a disastrous World Cup campaign, his reputation in tatters following the team's group stage exit on home soil.
On Saturday, he helped Leinster to a 15-12 victory over Racing 92 in the Champions Cup final, earning the province a record-equalling fourth triumph in European rugby's most prestigious club competition.
Johnny Sexton was quick to pay tribute to his team's unusually titled "senior coach" alongside head coach Leo Cullen.
“Stuart Lancaster, what a special coach to come in and do what he’s done,” Sexton said.
"Stuart came in and revolutionised the way we train and the standards we expect of each other," said backrow Dan Leavy.
“Stuart has brought a lot of insight into the English sides. How they work, how they tick.”
Lancaster cut a forlorn figure after England’s chastening defeats by Wales and Australia at Twickenham which ended their hopes of reaching the 2015 World Cup knockout stages.
He accepted full responsibility for the team’s performances after nearly four years in charge, and travelled the world to broaden his rugby experience before joining Leinster two years ago.
“It means a huge amount to me, my family and friends - they are the ones that all stood by me in my tough times after the World Cup,” Lancaster said after helping Leinster to win Europe’s premier club competition for the first time since 2012.
“They have never once wavered in my belief and ability and that is the nice thing. To have my wife here and son - and Sophie at home - that is for them really.”
Saturday’s final could have gone either way as Racing were never behind until Isa Nacewa’s 79th-minute penalty won the game for Leinster.
Sexton said: “We couldn’t get going and they came out and slowed us down at the ruck, which is obviously the way to beat us.”
“We did it the hard way. I never thought two or three years ago that this was going to happen again.”
Leinster had scored 31 tries in their eight Champions Cup games this season but they never broke the deadlock as Racing defended furiously throughout a tight match.
However, they benefited from Racing’s lack of discipline and Nacewa scored the decisive penalties with Sexton carrying a groin injury.
"We made it hard for ourselves but we got the win and that is all that matters," said man of the match James Ryan after Leinster finished the competition unbeaten.
“The line speed and the pressure they brought was unbelievable. We all worked our socks off out there - it was our toughest match of the season and just unbelievable to win.”
