http://metro.co.uk/2013/11/24/doctor-who-steven-moffat-clears-up-the-whole-doctor-regeneration-problem-sort-of-4199592/
‘Paul McGann turns into John Hurt so they’re not the same incarnation,’ said Moff. ‘He used up another regeneration and I’ll expect he’ll be in trouble shortly – you can’t break rules laid down in The Deadly Assassin.’