Hitech GP ace Dunne has been the class of the field in the revamped category this year but couldn't quite seal the crown with a round to go at Silverstone last time out as Gray claimed a win and the title contenders clashed several times.
That meant Gray retained the remotest possible chance of snatching the title at Brands, provided he qualified 17th or lower and won all three races, therefore earning sufficient bonus points from places gained in the reversed-grid contest to overhaul Dunne.
But, with Gray setting the second fastest time in qualifying, his title hopes are now over.
However, a penalty Gray received for one of the collisions at the tempestuous Silverstone meeting has been appealed to the National Court, meaning Dunne's success remains provisional.
Despite only formally lodging his entry on the eve of the season beginning, Dunne has been the driver to beat this year, the Irishman winning 11 races.
INSIGHT: The second-generation racer taking British F4 by storm
He stamped his authority on the new-look championship - which switched to a Tatuus-Abarth chassis/engine combination for this year as British governing body Motorsport UK took over as promoter - right from the first round, taking two wins and a second at the Donington Park opener.
He continued to rack up the victories from then on, breaking the record for the most wins in a season, and only failing to win at two events - Knockhill and at Silverstone two weeks ago.
In contrast, Williams junior Gray has only triumphed twice so far in 2022 and no other driver has won more than three times.
A difficult weekend for Carlin racer Gray at Thruxton at the end of August put Dunne into a commanding position heading to Silverstone and, despite not yet officially sealing the championship, he chose to skip the Brands Hatch finale to continue his campaign in the Italian F4 series at Monza this weekend.
Dunne, who sits third in the Italian standings, has recently taken part in a training camp with Ferrari and is eyeing a partnership with the brand as he moves up the single-seater ladder.
He is not the only driver to seal a British Touring Car support series title on Saturday with James Kellett becoming the final ever Ginetta GT4 Supercup champion - the series is being scrapped for next year - after finishing a close second in the opening race.
Century Motorsport driver Kellett, who has also broken the record for most wins in a season, could not quite seal the crown with a win as a bold move around the outside of rival Tom Emson at Hawthorn was unsuccessful.
Sam Weller has also secured the Mini Challenge spoils having taken fourth in the first Kent race.
The Hybrid Tune racer has enjoyed a supremely consistent season - finishing every race inside the top six so far - to impressively defeat a packed field of rivals.
