Victor Gollancz was Orwell's first publisher and the founder of the Left Book Club through which he commissioned Orwell to write The Road to Wigan Pier, the conclusions of which he did not agree with. Gollancz published Orwell's early novels, but published nothing of his after Wigan. They parted ways when Gollancz refused to publish Animal Farm on political grounds, not wanting to offend Britain's wartime Soviet allies or Soviet supporters among his own readership.
The Gollancz office did not look particularly occupied in 1999. Gollancz himself died in 1967, and I don't know who if anyone carried on the publishing company after him. For all I know, the office has been deserted for thirty years.