"Highlights for me would be my first Ranfurly Shield game [Counties v Mid Canterbury in 2014] and refereeing the Lochore Cup Final in 2008 between Poverty Bay and Horowhenua Kapiti."
Bay of Plenty and All Blacks hooker Nathan Harris wished McDermott well for the future.
"In my earlier years of playing for Te Puke he was not the guy we wanted to get on the wrong side of but towards the end we knew he was a good guy.
"I always give him stick about when I played for Chiefs Development against Fiji A. I thought Gappy had reffed the game really well but their captain got up and said 'referee, I think you need to do a few more sprints and work on your yo-yo'.
"Gappy after that worked so hard and he used to say he was the best at the yo-yo among the referees. He is a top guy and I wish him all the best."
Bay of Plenty coaching director Clayton McMillan agrees he will be missed out on the field.
"We forgive him for being a Southlander, first and foremost. He has always been thoroughly professional and manages to find that balance between being professional in his job and having that human touch," McMillan said.
"In my opinion some of the referees who have come out of playing representative rugby have a natural feel for the game. I have always enjoyed the way Gappy refereed both at club level and representative level. It will be sad to see him hang up the whistle actually."
McDermott is grateful to the support he had from other referees but mostly from his family.
"The major thanks needs to go to my wife Lisette who has been a rugby widow on many, many weekends over my career. Along with my boys Caide and Lucas, she has been the rock through lots of ups and downs and always there to support."
McDermott will continue to referee in the Bay of Plenty Rugby Premier competition in 2018 as he is still a few games shy of controlling 100 Premier matches. He will continue his involvement in Mitre 10 Cup, Super Rugby and test rugby as a television match official.