The 420-acre Sandley Stud stands five sires led by Generous, the 1991 Epsom Derby (Eng-i) winner.
Lomas won the award (£2,500 for himself and £1,000 for the other staff at the stud) from the two others short-listed, Lawrence Carling, yearling manager at New England Stud, and Sarah Sarson, stud groom at the Elms Stud, who each receive £1,000.
He said: "I have been in racing for 41 years. It is an honor to be here and a surprise to receive this award. I am lucky that I enjoy my job, and I get a lot of satisfaction from it."
Lomas has a wealth of experience having started out working at Whitsbury Manor Stud when it was owned by bookmaker William Hill and had stallions like Ballymoss.
He stayed for 10 years at Whitsbury Manor in Hampshire , spent six years working for James Delahooke in Berkshire, and then had a spell at Britton House Stud in Somerset before joining the Sandley Estate 15 years ago.
The Sandley stallions breed three times a day during the season, at 8 a.m.,1 p.m., and 5 p.m., and advances in veterinary science have made covering a much more precise science, with most mares getting in foal straightaway.
Sandley was purchased in 2004 by Alfie Buller, whose main stud is Scarvagh House in Northern Ireland.
The judges, led by Brough Scott, editorial director of The Racing Post newspaper, reported: "Stephen is extremely knowledgeable about nutrition and feeding, which means the stallions look immaculate and are a credit to him.
"He lunges the stallions each day each day before the season to build up their fitness, and he is very experienced in the breeding shed where his well-judged handling ensures everyone’s safety.
"He was particularly excited when Her Majesty the Queen sent one of her mares to be covered by Generous and waits with interest to see the foal that is produced."
The Stud & Stable Staff Awards, with £50,000 in prizes donated by Godolphin, are in their third year. Four stable staff -- newcomer, rider/groom, senior staff, and special merit/hero -- also receive awards.
Chris Hinson, 59, who won the senior category, also captured the employee of the year award with its £10,000 prize and another £10,000 to the other staff at Ed Dunlop’s yard, where he is head lad.
He was dual Breeders’ Cup winner Ouija Board’s regular rider.