It won best film, best director, best debut director and best screenplay for Wells, 35, as well as prizes for editing, cinematography and music supervision.
Aftersun, the devastating drama about a father/daughter holiday to Turkey in the late 1990s, has swept the board at the British Independent Film Awards (Bifas) in London.
The Richard Harris award for outstanding contribution by an actor to British film was presented to Samantha Morton.
Kathryn Ferguson’s study of the activism of Sinéad O’Connor, Nothing Compares, won best documentary and best documentary director.