Bradbury followed up his opening course record-equalling 63 with a 66 as he continued to make the most of a sponsor’s invite to Houghton GC.
But he was just one stroke clear when play ended for the night, following a long stoppage for an earlier thunderstorm, as Romain Langasque and a stunning late charge from teenager Casey Jarvis closed the gap.
Having dropped an early shot at the second, Bradbury responded in fantastic fashion by picking up six shots over the next five holes.
Two successive birdies were followed by an eagle at the par-five fifth – for the second day running – before further gains at the sixth and seventh as he matched Thursday’s outward nine of 31.
Birdies at the tenth and 11th kept up his momentum and though the remainder of the back nine petered out somewhat with bogeys at the 15th – following Thursday’s double bogey - and 16th he remained happy with his day’s work.
“I had it going on the front nine, I thought it was going to be another 63 or 62 even,” he said. “Back nine I made a few mistakes but overall very happy.
“Fifteen… I don’t really like that hole! Seems that way anyway - I missed it in the wrong place, and then I three-putted 16, again just missed it in the wrong place.”
Nevertheless, the Yorkshireman admitted he had surprised even himself with his opening two rounds.
“You always dream of it, that’s what you try and do, but it is a little bit of a surprise if you’d said it at the start of the week,” he said.
Langasque went birdie-eagle at the second and third and then posted three birdies in four holes round the turn.
He was 12 under for the tournament with seven holes of his second round to complete on Saturday morning.
South African Jarvis surged into contention with an astonishing run of seven straight birdies to leave him alongside Langasque in second.
Having started on the back nine, a solitary birdie in his first seven holes gave no hint of what was to come after the stoppage as four straight threes from the 17th kick-started his run. He too faces an early start on Saturday to play the final four holes of his second round.
Daniel van Tonder followed Bradbury 24 hours earlier in matching the course record, four birdies in each half of his round lifting him from two under par after his first round to ten under.
“It was fun,” the South African said. “I just got on a roll.
“I’ve been playing well the last seven months, the results just didn’t show it. Finally got a low round in so, happy.”
Sami Välimäki was similarly impressive to Bradbury on the front nine, opening with four birdies and an eagle in eight holes before play was suspended just after 2.30pm local time.
After the resumption, the Finn could only manage three straight pars followed by a bogey at the 12th to join the group in fourth place - which also included Nathan Kimsey, who made two birdies in his last three holes of the day and was left with four to play.
Defending champion Thriston Lawrence ended the day on six under after just two birdies and a bogey in his 11 holes.