Oldfield had the biggest success of his career when he won a six-man blades final of five sheep each by almost 5pts from the England World Championships pair of veteran George Mudge and son and 2016 winner Andrew Mudge.
The victory was 26-year-old Oldfield's third win in the UK in the last month, the first at Fernhill and the second at the Devon County show a fortnight ago.
A year ago Oldfield achieved the unique treble of three wins in the UK - his first wins as an Open-class bladeshearer, as a Junior machine shearer, and as a Novice woolhandler.
At the Bath and West Show her also teamed with England-based form Dannevirke shearer Michael Churchhouse to win a teams match against the Wales and England World Championships teams.
Results from the British Golden Shears at the Royal Bath and West Show, England, on June 1-2:
Open machine shearing final (20 sheep): Matthew Smith (New Zealand) 13min 52sec, 53.65pts, 1; Gwion Evans (Wales) 14min 43sec, 55.1pts, 2; Richard Jones (Wales) 15min 15sec, 56.05pts, 3; Jack Fagan (New Zealand) 16min 9sec, 58.1pts, 4; Ian Jones (Wales)16min 12sec, 59.25pts, 5; Dean Nelmes (England) 16min 28sec, 66.85pts, 6.
Open blade shearing final (5 sheep): Allan Oldfield (New Zealand) 17min 18sec, 82.2pts, 1; George Mudge (England) 18min 28sec, 87.1pts, 2; Andrew Mudge (England) 18min 25sec, 87.35pts, 3; Elfed Jackson, (Wales) 18min 37sec, 91.55pts, 4; Danny Wilson (England) 21min 57sec, 101.65pts, 5; Clive Hamer (Wales) 20min 1sec, 107.35pts, 6.