The man who bought London by Edgar Wallace

I liked reading it. All of Wallace books sound so terribly old, of course, but one thing I must give to him: he very well knew how to write. The characters are interesting and catching, and I wanted to see them to the end. I love this King Kerry, and Elsie Marion too. It was a fine story which would make a lovely film. I wonder, how come his books have inspired no films, it's extraordinary, if adapted they could make great screenplays! I don't know, maybe there are and I simply don't know about them..
Elsie is a normal girl, working at the counter in a clothes shop, or something like that, when one day her luck changes. She meets American millionaire King Kerry. He was buying a lot of London shops and properties, and he bought the one she worked in too. He took her as his personal assistant, and obviously she fell in love with him. He has grey hair, but must be 35 to 40 years old, no more.
He plans to buy all the land within the territory where he wants to build a new city of London, with new houses for everyone and better shops. I have no knowledge of all those places' names; he bought so much, papers called him "the King of London", and also "the man who bought London".
His worst enemy is Hermann Zeberlieff, who had tried (not honestly) to go against him in business and had always been scorned. He lives with his half-sister Vera because forced by their father's will, but as soon as possible she gets free of him. She lived in fear, near him, afraid for her own life, and could get out only with Kerry's help. A great scene was when Hermann came to her about Gordon Bray. Bray is a young and good man, poor but with talent and ambitions, and very much in love with Vera, apparently requited. When he learned that, Hermann drugged him and locked him up in his wine cellar, then went to Vera saying "at what figure do you value his life?" because he wanted her money, and then I got it. For a moment there I thought Edgar had betrayed me by killing a good-lovable character, but no, Hermann was just using him to get his sister's money. She was pale and deadly afraid for him, so much more than she had ever been for her own safety, but also she felt the hate rage inside her. For an instant, when she went to her desk I thought, is she really giving him a cheque? But no, she takes out a revolver aiming it at him, who gets scared, and when she fires so near to him he's really scared, and then she tells him quietly "I want to tell you that if any harm comes to Gordon Gray I will kill you, that is all. Now get out" :-) Vera was great! :-) I loved that scene :-)
Unfortunately the end of the book wasn't as good as the rest. It turns out that young Kerry married Vera's half-sister Henrietta and that story might now ruin his reputation and his future happiness with Elsie because Henrietta is evil, dishonest and probably mad as her mother was. Yet it all ends in a moment when trying to kill him Herman kills himself instead and it is revealed that he's actually a woman: Henrietta! (By the way, that suicide girl in his past was not killed but had really committed suicide after discovering that the man she had fallen in love with was actually a woman. Suicide! My God, what were the girls back then??)
The threat is now gone, and he's no more married, so he can marry Elsie and Vera can marry Gordon, and a happy ending it is for all the good characters in the book :-D
I wonder, would it be possible, in a film with real people, to pass a woman for a man for at least 3/4 of the film , really making people believe it's a man?