Thompson takes over the entry occupied at Knockhill last month by Rob Huff and will see out the season this weekend at Silverstone and next month at Brands Hatch.
Reigning Jack Sears Trophy champion Thompson starred in the first half of this season, qualifying fourth at Oulton Park, but was forced onto the sidelines thereafter when 2020 JST title winner Michael Crees brought a budget to return to the BTCC.
Nic Hamilton then abruptly quit the team on the morning of qualifying for the following round at Croft, creating the vacancy that was filled by 2012 World Touring Car champion Huff at Knockhill.
After missing the interim round at Donington Park due to clashing TCR World Tour commitments, Huff was tipped to return for Silverstone and Brands.
The 43-year-old has decided instead to stand down but is weighing up a return to his domestic championship for next season, 20 years after his only full-time BTCC season as a tin-top rookie with the works SEAT squad in 2004.
“It was great for Tony [Gilham, Hard boss] to get me in the car at Knockhill, but unfortunately the stars haven’t aligned for the rest of the season,” Huff told Autosport.
“I will be attending Silverstone on Saturday to speak to teams about potential opportunities for next year for sure.
Source: Autosport