Roy, 41, (42 on Jan 21) took a few minutes off his gardening duties for a mid-morning celebration with his fellow workers at the insistence of Trewithen's owner, Michael Galsworthy.
He was presented with an engraved tankard that Mr Galsworthy promised to fill with beer for him at the end of the working day – although for the purposes of the party it was strictly tea and cakes only.
"This is what I call a family celebration!" said Mr Galsworthy. "I have always said that everyone at Trewithen is part of the family, we have extremely good solidarity here. We've only had three head gardeners in the last 100 years."
Mr Galsworthy went on the congratulate Roy for his excellent work over quarter of a century that has seen both good and difficult times at Trewithen. He particularly thanked Roy for his help during and after the hurricane of October 1987 when he played an essential role in saving and clearing the affected trees and working to restore Trewithen's award-winning beauty.
"Today the focus is on you Roy. We are here to celebrate 25 years of what is an outstanding achievement. We are hugely grateful for all you have done and I look forward, if you can stand it, to working with you for another 25 years."
Roy joined the Trewithen team as part of the Government of the time's Youth Training Scheme (YTS) just six months after leaving school. His potential and passion for gardening was spotted and he was offered a full time job as his YTS came to and end.
"I was so pleased to be offered the job," said Roy. "I had always loved gardening as a boy. I started by helping my dad grow vegetables but I was always more interested in shrubs so working at Trewithen has been perfect. Spring time at Trewithen is so special when everything is budding and turning into bloom. I've stayed this long because I enjoy it, but it really doesn't feel like 25 years."
Roy's co-worker, Neil Trebillcock, is next in line for the silver service celebration in seven years time. He too joined the gardening team straight from school on the advice of his father, Ronald, who worked at Trewithen until retirement.