Having set a quick lap time of 1.26.13 early on in the session, fellow drivers did all they could in an attempt to snatch his provisional pole, to no avail.
Team mate Sam Tordoff was also quick, securing second place behind his KX Momentum Racing team mate – achieving his best qualifying result to date in his first full year in the series.
Lining up third is defending champion Gordon Shedden, who near the beginning of the session had his quickest times removed having exceeding the track limits. Team mate Matt Neal, who was carrying full championship ballast, had an unfortunate session – including an off at Hislop Chicane and ended up on the fourth row in eighth.
The Speedworks Motorsport Toyota impressed at the hands of Dave Newsham, as he set a quick time as the session was ending to put him in fourth ahead of free practise two leader Andrew Jordan and the sister Toyota of Dynojet racer Frank Wrathall.
Tom Onslow-Cole, who also had a moment at the Hislop Chicane, managed to get his Team HARD run Volkswagen Passat CC into the top ten, with Airwaves Racing Mat Jackon in eleventh. Team mate Aron Smith had to settle for seventeeth ahead of Austin – running a new Swindon engine in his NGTC Audi A4 - who had to pit during the session for a broken bonnet.
Lea Wood secured the Jack Sears' pole position in nineteenth.
With warm conditions forecast, tomorrow's action begins just before 12:30 in what's set to be an action packed day throughout the package. You can tune into to ITV4, where the team will provide you with all the information you need to know.
1. Jason Plato
2. Sam Tordoff
3. Gordon Shedden
4. Dave Newsham
5. Andrew Jordan
6. Frank Wrathall
7. Colin Turkington
8. Matt Neal
9. Adam Morgan
10. Tom Onslow-Cole By Nikki Thompson