film company whose symbol was a large gong

The film company you’re thinking of is The Rank Organisation (often referred to as J. Arthur Rank).

What the logo looked like

• A muscular man (the famous “Gongman”) stood in front of a huge gong.

• He struck the large gong with a mallet, accompanied by a deep, resonant gong sound.

• This sequence appeared at the start of films distributed by General Film Distributors and later The Rank Organisation from the mid‑1930s onward.

Extra bit of trivia

• The gong in the logo was actually a prop made of plaster or papier-mâché; the real sound came from a smaller Chinese tam-tam gong played by percussionist James Blades.

• The earliest versions featured boxer “Bombardier” Billy Wells as one of the Gongmen, becoming an iconic image of British cinema.

TL;DR: The “film company whose symbol was a large gong” is The Rank Organisation, famous for its Gongman logo at the start of its movies.