The veteran Newmarket handler has enjoyed a stellar career. He won every British Classic at least once apart from the Epsom Derby, although he famously sent out Terimon to finish second at 500-1 to Nashwan in 1989.
He also enjoyed a formidable partnership with Yorkshire jockey George Duffield, most notably with the English, Irish and Yorkshire Oaks in 1992 before landing the St Leger.
Asked why he felt now was the right time to call it a day, Brittain, 81, said: “Old age would probably be a hint, but I want to spend a few years looking after my wife. She’s spent 60-odd years looking after me, so I think it’s only fair I spend some time looking after her.
“Where there’s a beginning there’s an end and I just felt the end was nigh. This is the right time to do it.
“I’m retiring with some regret, as I’ve had some fantastic owners over the years and still have, as well as great staff.
“I’ve lived a charmed life.”
Brittain enjoyed his first taste of Classic glory with Julio Mariner in the 1978 St Leger, a race he later won the the aforementioned User Friendly.
He saddled two winners of the 1000 Guineas at Newmarket in Pebbles (1984) and Sayyedati (1993).
Pebbles was perhaps Brittain’s greatest ever horse, also winning the Champion Stakes, the Eclipse and the 1985 Breeders’ Cup Turf.
Brittain won the 2000 Guineas with Mystiko in 1991 and Terimon enjoyed his day in the sun when claiming the Juddmonte International that year.
He broke new ground for British trainers when Jupiter Island and Pat Eddery lifted the Japan Cup in 1986.
Honourable mentions also go to dual Coronation Cup winner Warrsan, the globetrotting Luso, multiple Group One-winning filly Crimplene and his latest top-level scorer Rizeena.
A Group One winner in the Moyglare Stud Stakes as a juvenile, she won the Coronation Stakes at Royal Ascot last summer but having failed to reach those heights this season, Brittain has also called time on her career.
He said: “Rizeena won’t run again. The decision was left to me and we just felt she hadn’t quite reached the heights of last year.
“She’s done so much for us in the last couple of years and we decided we wanted her to go on at the top.”