Collingbourne left it late in the session to post his best time of one minute, 32.535 seconds but then also produced two more laps good enough for a top six position.
Team Pyro’s Bushell, who took over the championship lead at Oulton Park two weeks ago, was 0.178s adrift but behind him the gaps were even closer as less than a second covered the top 13 runners.
Finesse’s Streather was a mere 0.087s slower with the margins between the next three drivers – his Ecomotive-backed team-mate Daniel Rowbottom, JamSport’s Ant Whorton-Eales and Ciceley’s Max Coates – even tighter at just 0.069s, 0.043s and 0.044s respectively.
Pyro pair David Dickenson and Josh Price, 4Front Motor Group with WDE’s Paul Rivett and JamSport’s Luke Kidsley completed the top ten.
Collingbourne, aged 18, said: “It’s not been the best start to the season for me so I’ve made an effort to change my approach in recent weeks.
“I also did quite a bit of simulator work mid-week and for the first time this season I feel really at one with the car. It’s a good start to the weekend – I just need to keep building on it.”
Bushell added: “I think Rory got a good tow in my slipstream there on the run from the chicane down to Tower Bend which helped him! But he’s still done a good job to be fair. I’m quite happy with that – we’ll see what new tyres can do for us in this afternoon’s session.”
CLICK HERE for full times plus sector and speed trap readings from the above practice session.