Thanks to Kare for finding this synopsis of Of Corset’s Mine at TheFilmCatalogue.com, which includes more information about William’s character Randolph:

Its 1871 and sisters Henrietta and Daphne Merryweather are shocked to learn from their mother that, due to a stipulation in their father’s will, they have only weeks to marry or else they lose their inheritance and fortune to their unscrupulous cousin Basil. With limited time, their one glimmer of hope lies in the impending visit of eligible bachelor Trevor, along with his sister Jane.

When their rogue philanderer brother Randolph stumbles home from the pub, he fails to grasp the severity of the situation and begins to chide his sisters about how easy women have it. In order to teach him a lesson, they dress him up as ‘Randolphia’ however their fun is short lived as their visitors arrive a day early and Randolph has no option other than to remain as his newly adopted female persona.

Before long the trio find themselves trapped in their lies tighter than Randolph in a corset! What ensues is a hilarious comedy of mistaken identity, sibling rivalry and the fluttering of fans, as they hurtle towards a Merryweather wedding – but just who is getting married?