His initiative in interviewing many largely forgotten, elderly film pioneers in the 1960s and 1970s preserved a legacy of early mass-entertainment cinema.

Writing fan letters to silent film directors, he began to strike up a correspondence with figures from silent-era cinema.

[5] Brownlow's interest in the Second World War prompted the creation of his alternative-history film It Happened Here, premised upon the Nazis having conquered Britain.

After eight years of struggle, during which the film's content changed dramatically, it was completed in 1964 with the last-minute aid of Tony Richardson.

After the run, UA reported to Brownlow and Mollo that all of the box-office receipts had been used to pay the advertising and distribution costs.

The book features many interviews with the leading actors and directors of the silent era, and began his career as a film historian.

He spent twenty years gaining support for the restoration of Abel Gance's French epic, Napoléon (1927), a then-mutilated film that used many novel cinematic techniques.

Since Gill died in 1997, Brownlow has continued to produce documentaries and conduct film restoration with Patrick Stanbury.

It tells how Brownlow has spent 50 years of his life piecing together the lost sequences into the latest restoration of the silent movie and about his meeting the dapper Gance when still a schoolboy.

In April 2019, Brownlow was honored at the Turner Classic Movie Festival in Hollywood at a screening of It Happened Here at Grauman's Egyptian Theatre.