I'm not sure it's as simple as "clause or no clause". My understanding even before now was that there was a clause, but that we said it committed us only to letting the player know of the other cub's interest, as opposed to the argument from Suarez' agent (and the player himself at the time) that it committed us to letting him go. As I recall, the PFA's legal dept.looked at it and agreed with our view.
So essentially Henry is just grandstanding with those quotes.
If Arsenal could've taken us to court to get him for £40m, they surely would have done.