My favourite book and how I'd cast it for a movie

 I've decided to go a little off-piste for this topic from Long and Short Reviews, as I was struggling to think of a favourite book of mine that hasn't already been made into a film. My automatic response when I like a film is to check out the book. So I decided to do this with my favourite of my own books, because I would love to be able to cast it for a film.

Photograph has one particular trick in that the two heroines are fraternal twin sisters - as written, Tara and Azure are facially identical but have opposite colouring. As a result, I would prefer to cast one actress in a dual role and have her wear wigs and coloured contact lenses. My favourite actress for this role would be , who I've loved in every film I've seen her in.

For Tara's love interest Ryan, I would cast . Ryan is American, but I'm pretty sure Taron Egerton could manage an accent. I loved him in the Kingsman films and also Rocketman.

For one of the side characters, Tara's roommate Kiki, I always saw . She's possibly a little old for the role now but I don't believe I ever stated Kiki's age, so I don't think that would matter.

The most difficult character to cast would be Liam, Azure's husband, who is a celebrity theme park owner and was originally inspired by Gene Wilder's performance as Willy Wonka. I eventually settled on . He's very good at playing genius characters.

So which book would you like to cast for a movie?