Duckster
Tour Rookie
I expect that the confirmation Rulefan is waiting for will be from the R&A.
I dropped the R&A a question about it last night and have just had this response (I stand corrected as I was the one who added the part about announcing first then dropping).
Dear Adam
Thank you for your email and query on the Rules.
Under Rule 27-2a, if a player fails to announce that he intends to play a provisional ball and plays another ball, that ball is not a provisional ball. Therefore, the player can drop the ball and provided he makes the statement to the effect that it is a provisional ball prior to playing it, it is a provisional ball played in accordance with Rule 27-2a.
That's that settled then.