Next weeks TV Times (out today in the UK) has a picture of Matthew Macfadyen as Arthur Clennam in Little Dorrit wearing his hat. The article is part of a double page spread about forthcoming Autumn productions.
According to JaneV the article says:
If you love a good period drama then this is for you. Andrew Davies adapts the Dickens classic, with newcomer Claire Foy as the heroine Amy Dorrit, and ex-Spooks star Matthew Macfadyen as the kind Arthur Clennam. Amanda Redman is also in the all-star cast. "I play an appalling snob and get to wear outrageous costumes," she tells us.
Thanks to timmytiger, JaneV and 6point7 for the unified efforts to bring this news to us.