Which English studio hosted Supergirl's principal photography?

Supergirl’s principal photography was hosted at Warner Bros. Studios Leavesden in England.

Leavesden is a major film and media complex in Leavesden, Watford, Hertfordshire. The production also filmed in London and Scotland, but Leavesden was the English studio facility associated with the film’s principal photography. Its stages, workshops, production offices, and backlot support large-scale effects-heavy productions such as Supergirl.

The site began as Leavesden Aerodrome and was converted from aircraft-related industrial buildings into film stages. Warner Bros. acquired the complex and completed a major redevelopment, creating one of the company’s most important permanent production bases in the United Kingdom.

Pinewood, Shepperton, and Ealing are also famous English film studios, which makes them plausible distractors. However, they are not the studio named for Supergirl’s main production base. Leavesden is also sometimes shortened in conversation to “Leavesden Studios,” but the formal name is Warner Bros. Studios Leavesden.