Huge cranes, trailers and hospitality vehicles have been seen at the airport in Kemble, sparking speculation a major production is being filmed there.
Sources say crews were shooting scenes, during the night, for Alex Rider 2.
Eleventh Hour Films has been producing the second season, which is based on the best-selling novels by Anthony Horowitz.
The collection stars Otto Farrant, who was also in Mrs Wilson, as Alex Rider alongside co-stars Vicky McClure (Line of Duty), Stephen Dillane (Game of Thrones), Brenock O’Connor and Ronke Adekolueja.
The series follows Alex Rider, a London-based teenager who has unknowingly been educated since childhood for the damaging world of espionage.