lauded Don Carlos with Derek Jacobi, and dramatises the tumultuous final days between Elizabeth I (played by Janet McTeer) and her cousin Mary, Queen of Scots (Harriet Walter).
'In the court atmosphere of that time, the only place you can relax is in your own bed,' Kinnear says. 'And even then you're not safe from attack. Every character has to wear a mask. To have to do that just to survive is extraordinary.'
Kinnear plays the courtier Mortimer, a young man caught between two supremely powerful women. 'He is the real "sturm und drang" of the play. Although you can't play a literary movement, he's the representation of the Romantics in a play about Elizabethan politics.
Yes, it's a free interpretation but it's as lifelike as Richard III or Henry IV. It's a thriller.' And has he anything scheduled after Mary Stuart? 'Actors are very unpopular if they've got something lined up so, if I had, I'd have to keep it quiet. But no, I haven't.'
Is there anything he's holding out for? Remembering his childhood dream, he could play Sweeney Todd.
'That,' he smirks, 'could be the perfect marriage of my ambitions.'
Mary Stuart previews now, opens tomorrow, until Sep 3, Donmar Warehouse, 41 Earlham Street WC2, Mon to Sat 7.30pm, Thu and Sat mats 2.30pm, £15 to £29. Tel: 0870 060 6624. www.donmar-warehouse.com Tube: Covent Garden.