That's right Bob -
He niched his market in two areas actually, both related to his trade. His printing company used, I believe, to specialise in printing scripts.
His other angle was occasionally he'd buy 'job lots' of theatre scenery from closed productions and hire them to other companies. Good strings to have to your bow when 'resting'.
Walter Gotell (character villian and occasional Russian in 007) was also a successful businessman as well as an actor - he ran a number of engineering firms.