Moeen Ali cannot bowl a doosra (or, at least, not a useful one - or so I predict)
I am delighted that Moeen Ali bowled so well in the Southampton Test against India - and I am not at all surprised.
He has a really nice classical off-spinner's action, and spins the ball almost as rapidly as Swann (and considerably more rapidly than either India's Jajeda or of Sri Lanka's Herath).
But I predict that Moeen will not be able to bowl a doosra - at least, he will not be able to bowl a useful doosra at teh test match level (i.e. that a delivery that is legal, hard to pick, reliable and effective). This is simply because he has a classic off-spinners grip and action - holding the ball between index and middle finger and delivering it from the front of the hand; and a doosra cannot be bowled with that kind of grip and action (nobody has ever done it).
The fact that Moeen has been tutored by Saeed Ajmal at Worcestershire is irrelevant; since Ajmal has a completely different method. He grips the ball between middle and ring finger, and delivers both off-spinner and doosra with the back of his hand towards the batter and a forward flick of the wrist.
But Moeen does not need a doosra - he has already shown that he can beat the bat on both sides - even with very good players.
Given his excellent batting and superb temperament, England now solved their spin problem and have a really valuable all-round cricketer in Moeen Ali.