"Eighteen Tests and endless memories of club and international rugby later and I do not regret any moment.
"Every international I have been a part of has been a fantastic experience but the 2003 Rugby World Cup in particular is a memory that will stay with me for a very long time.
"However, at the top level of refereeing there are considerable demands on your time. You need to be 100% committed and at the moment I have other major constraints on my time. I do a lot of travelling between Wales and London and so for nearly 40 weekends to be taken up through rugby takes toll after a while.
"I am looking forward to spending some more time with my wife, Cheryl and our family and friends."
Despite the good times, Williams is adamant that unless organising bodies, clubs and fans take stock and start respecting the man with the whistle once more, we are heading for the situation football finds itself in.
"Referee abuse is a global problem that needs to be properly addressed. No game can go ahead without a referee so they are a vital part of the game but at the moment there is an unacceptable level of abuse from the top right down to grassroots level.
"Unless something is done to reverse the trend, we are heading down the same route soccer has gone down which is total anarchy on the pitch. There is absolutely no respect for the man in the middle and if we are not careful the same will happen in rugby," he said. "In a way what is happening on the rugby field at the moment is a reflection of society where there is a general lack of respect for other people. People think they can do or say what they want without there being any serious repercussions. That must change and I understand that is changing in Wales with clubs being held responsible for what happens at matches."
Williams is relatively confident that Welsh rugby is now on a firm footing.
"Welsh rugby needs stability. The Celtic League has its merits if all countries take it seriously and now the Powergen Anglo-Welsh Cup promises to be an exciting competition," he added. "The structure is improving and hopefully now, the conditions are in place for our good age grade prospects to be well looked after and treated like athletes. Hopefully, the revitalisation of the game since last season's success will also spill out into refereeing recruitment.
WRU Director of Match Officials Robert Yeman paid tribute to Williams: "Nigel has not only been a terrific servant to Welsh rugby, but to refereeing around the world. His career record speaks for itself and shows that despite the pitfalls referees can encounter, refereeing still provides an opportunity to meet people and travel the world.
"Nigel's departure leaves Wales with three IRB panel referees in Nigel Whitehouse, Nigel Owens and High Watkins but it also provides an opportunity for the younger element within the game to push forward their claims for inclusion in that list.
"I concur with Nigel's sentiments on referee abuse being a major problem with the game. The Welsh Rugby Union is continuing to take that seriously - following on from our campaign which began last January, we have taken action against a number of clubs and individuals.
"In terms of referee recruitment, our summer referee courses have had a healthy number of participants and hopefully these numbers will be translated into participation in youth and district refereeing."
As a player, Williams was capped at scrum half by the Welsh Schools Under 16 team and captained Wales Under 19 in the first World Sevens tournament. He switched to fly half while playing for his village club Bryncoch and then had a season with Neath "only for Jonathan Davies to arrive on the scene at The Gnoll."
He returned to Bryncoch where he served as player, captain, coach, secretary and treasurer before his uncle, the former international referee Clayton Thomas, persuaded him to take up refereeing.
NIGEL WILLIAMS CAREER HIGHLIGHTS
2002 - New Zealand v Italy (Hamilton); Ireland v Georgia (RWC Qualifier); Scotland v South Africa (Murrayfield).
2003 - Italy v France (Rome); Australia v Ireland (Perth); South Africa v Argentina (Pt Elizabeth); England v France (pre-RWC warm-up, Twickenham); Argentina v Namibia (RWC, Gosford); Japan v Fiji (RWC, Townsville); England v Uruguay (RWC, Brisbane).
2004 - Ireland v Scotland (Dublin); New Zealand v England (2nd Test, Auckland); South Africa v New Zealand (Tri-Nations, Johannesburg); Scotland v South Africa (Murrayfield).
2005 - France v Scotland (Paris); Australia v France (Brisbane).
1997 - World Cup Sevens, Hong Kong
2000 Final of Under 19 World Cup Australia v France
25 Heineken Cup games including:
2003 - Semi-final Leinster v Perpignan
2004 - Semi-final Munster v London Wasps
2003 - Parker Pen Challenge Cup Final, London Wasps v Bath, Reading
2003 - Inaugural Celtic Cup Final, Edinburgh v Ulster, Murrayfield
Welsh Cup Finals:
2003 Llanelli v Newport
2005 Llanelli v Pontypridd