Michael Winner's tenure working with Daniel M. Angel inspired him to produce his own films, so that he wouldn't have to deal with such interference. Winner remained vindictive about Angel for many years, although it is perhaps worth mentioning that his low opinion was emphatically not shared by many other significant figures in the British film industry, and that Angel's reputation as a producer was generally a high one. It has been widely doubted that a man of his acumen would have turned down Sean Connery or James Mason for leading roles.
According to Michael Winner, James Mason was the original choice for Richard Dyce, but Daniel M. Angel rejected him, feeling the actor was a has-been.
In the opening credits Alfred Lynch walks past a dilapidated house in Notting Hill. This is 25 Powis Square, which was later renovated and used in the cult British film Performance (1970).
Michael Winner wanted Oliver Reed for the role of Joe Beckett, but producer Daniel M. Angel rejected him for being a B-picture actor (which at the time Reed was). According to Winner's memoirs, Angel rejected Sean Connery for the same reason, though some have doubted this claim.
As was usually the case with Michael Winner films, most of "West 11" was shot on location as the director hated filming on sound-stages.