In the article "Couture Costume Drama: Anna Karenina draws on 1950's inspiration" the following was stated about Matthew Macfadyen's character:

To say nothing of the men's suiting, which was developed from each character's attributes. For example, Durran transforms Matthew Macfadyen from the swoon-worthy matinee idol Mr. Darcy he played for Wright earlier in Pride & Prejudice, into Anna's jolly hedonist brother Oblonsky. The pleasure-seeker's lust for life and humour is inherent in his costumes, with brightly coloured suit jackets, wide notched lapels and oversized cravats, all of which reflect his outsized personality. "His performance is larger than life, isn't it?" Durran laughs. "Matthew is larger, physically (the actor is six-foot-three) - I think you build on his size, really, and you don't try to minimize it in any way. The first time you see him on the stag being shaved by the barber, he is wearing that huge printed velvet robe - it was just to make him that much more larger than life."

"I remember from the book he is always the one spending all the money, and poor old (wife) Dolly doesn't have anything. She is trying to scrimp and save. That also played into Oblonsky - he has hunting clothes, he has everything for every occasion, he had all these costume changes, and they're all big because he and his personality are big."