Horace Ové, a prolific and groundbreaking Trinidad-born filmmaker and photographer whose 1975 film, “Pressure,” explored the fraught experience of Black Britons and is considered the first feature film by a Black British director, died on Sept. 16 in London. He was 86.

The cause was Alzheimer’s disease, said his son, Zak.

“Pressure” was made on a shoestring, shot in West London with neighborhood characters and Mr. Ové’s friends from film school volunteering their expertise. It was written with Samuel Selvon, a novelist from Trinidad, and it tells the story of Tony, a first-generation Briton and top student who has just graduated from school shouldering the expectations of his traditional West Indian parents and his own ambition, and navigating a community on the boil.

As he looks for a job to match his talents, he slowly realizes his is a fool’s errand in racist London. Tony’s older brother is a Black militant — born in the West Indies, he has no illusions about…