Jan Ravens as Netta Flowers
Who Is She? Marigolds mother and Michaels husband. Like Michael, shes obsessed with preserving the Earths resources and is incredibly open about her sex life (at one point its mentioned that she took all the locks off the doors in her house and walked around naked), disgusting her step-daughter Daisy and unnerving Adrian.
Why Jan Ravens? Shes a very a versatile actress with a particular speciality for comedic roles. Netta is largely used for comic relief, especially when threatening to sue Adrian for breach of promise (a long since abandoned part of the legal system that allowed people to be sued for breaking off an engagement) and openly discussing her plans to leave Michael with her entire family and Adrian. Also, Ravens has played some quite bohemian characters before, which makes her a good choice in my book.
Richard Armitage as Hugo Fairfax-Lycett
Who Is He? Mangold Parvas (Adrians village in The Prostrate Years) local aristocrat, owner of Fairfax Hall (the villages stately home) and descended from slave traders. Hes an object of desire for both Adrians mother Pauline and wife Daisy, later having an affair with the latter causing Adrian and Daisys marriage to collapse.
Why Richard Armitage? Hes got a strong body of work behind him and can capably pull off comedic roles as well as dramatic ones. As well as this, he definitely seems like he could be an object of desire for a lot of women and has a vaguely aristocratic look to him.