The Carnegie director of rugby will take up a prestigious role as head of elite player development with the RFU in June after deciding to end his long association with the club.

Lancaster, 38, insists it was a decision he didn't take lightly, but the "once-in-a-lifetime" opportunity of working with the cream of union talent in England proved too strong a lure.

Lancaster, who will replace Conor O'Shea – who moves to the English Institute of Sport – said: "It's a fantastic opportunity, to be honest.

But given my time at Leeds – I've been with the club for 16 years – I've a huge emotional attachment to the place, so it's been a hugely difficult decision.

"I certainly had a lump in my throat when I spoke to the players. They are the important ones and are growing as a team and getting stronger.

"It was made more difficult by the fact that I believe that – while being disappointed at getting relegated – Leeds have made massive strides in the last two years."

Carnegie are now stepping up their hunt for Lancaster's successor and expect to receive some high-calibre applications.

And despite being disappointed at the RFU approaching Lancaster without first informing them, Leeds will not take the matter any further or pursue compensation.

Twickenham officials insist the position was advertised after O'Shea indicated he would be leaving and that Lancaster applied for it in the standard way.

Headingley chief executive Gary Hetherington said: "We're disappointed with the RFU, but won't be taking it any further.

"We'll now move to appoint a new man. The first part of the process will be deciding who is interested and available and we'll be doing that in the next few weeks.

"Nothing is ruled in or out and we'll spend time looking for the best man available."

Potential front runners include ex-Rotherham and Ulster head coach Andre Bester – understood to be interested – and former Leeds director of rugby Phil Davies, available after recently being sacked by Llanelli Scarlets.

On the exit of Lancaster – who has served Leeds as a player, captain, academy manager and director of rugby – Hetherington said:"It's all happened fairly sharpish. In some ways, the timing of it at the end of the season has made it a bit better.

"I'm not surprised that others have been looking at Stuart. He's contributed so much to the club with the development of the academy and we're indebted to the role that he's played."