Urquhart equalled the record for nine holes on the Sunshine Tour, joining a select club including Simon Hobday, Mark McNulty, David Frost and Brenden Pappas as the only golfers to have posted a score of eight-under par 28 on one nine.
The 27-year-old Scot from Inverness, who is making his debut appearance on the local tour, went on to sign for a 64 around the Royal Swazi Sun course.
'That's easily the best nine I've ever played. It's funny how that happens. Everything just seems to click,' said Urquhart, who shares the tournament lead with Hilton at 12-under par 132.
The duo are two strokes clear of first-round leader Peter Wilson, Switzerland's Andre Bossert, American Bruce Vaughan and South Africa's Bradford Vaughan.
Urquhart turned in level par after what he described as 'an average front nine'.
But the catalyst came at the par-four 10th, where he holed out with a sand wedge from 90 metres for eagle. At the par-five 12th, Urquhart sunk a one-metre putt for another eagle, and then he reeled off four successive birdies for his 28.
'I nearly had a 27, but I lipped out from eight metres for a birdie at the 18th,' Urquhart said. Hilton completed the British domination of this tournament on the same day he celebrated his 23rd birthday.
But despite a round of eight birdies, the young Englishman was disappointed with his bogey at the last where he missed a simple putt for par from less than a metre. 'I'm not overly pleased with my finish,' Hilton said of the three-putt for a drop at the ninth.
'I three-putted the par-five seventh for a par, and then three-putted the ninth for a bogey. But I did hit a lot of good iron shots out there.' The ebullient Wilson kept himself in contention with a one-under par 71. But the rhythm that earned him the first round lead deserted the Englishman on Friday.
'I didn't hit as many fairways, and also didn't hit it as close to the flag as in the first round,' Wilson said. The dominance of the British golfers is surprising considering that most have been unable to practice at home because of the poor weather.
'When I went home in December, I thought I'd be a real professional and go and hit some balls one day, but it was snowing,' Wilson said. The halfway cut was made at one-over par 145.