The win enabled Thomas to walk away with two of the four trophies on offer at the Cycling Otago event.
Perfect conditions and a shortened course due to road works contributed to high numbers contesting the race.
Eighteen minutes separated the three front-markers from scratch riders Thomas, Mark Spessot and Brad Evans, with five much larger bunches in between.
The scratch bunch worked well together on the outward leg, averaging 44kmh and steadily gaining on the groups ahead of them.
On the homeward leg, they gobbled up the break group and this bunch of about 15 riders put on the pace on the approach to the finish.
It was not until 3km from home that they finally captured the front-markers, dashing their hopes of victory.
At 100m out, Spessot bolted in characteristic style. With Thomas on his wheel, the pair were eagerly pursued by the rest of the large amalgamated bunch.
Spessot looked like he had the edge over Thomas but, in a perfectly timed burst of power, Thomas edged his wheel over the line fractionally ahead.
Thomas' time of 57 min 47sec was testament to the speed in the final kilometres of the race.
Spessot did not go home empty-handed, however, as he was awarded the trophy for first masters rider home.
Indicating a fine job done by the handicappers, the bulk of the field finished just seconds behind the winners.
Elyse Fraser, Reta Trotman and Emma Sutherland started the race in the break bunch and were all in the hunt for first woman.
In a continuation of her recent good form, Fraser edged out the others to claim the trophy.
In what was a challenge for some, the junior riders raced in the main field.
Lachie McGregor, riding off break, was impressive, coming through to take hard laps at the front.
He has earned the respect of much older riders who praised his strength and hard work.
By Janice McClelland.
