Ball moved off tee - still hit it.

[funk-like]

I played today, and my playing partner was just about to tee off. After addressing the ball, and starting his backswing, a gust of wind moved the ball off the tee, it fell off just as my partner was 1/2 way through his downswing. He could not stop his swing, and continued to swing at the ball, which he hit. The thing is, the ball was still moving (after just having fallen off the tee) when he hit it. He actually made good contact and hit it in the fairway.
What is the rule in stroke play? 1 stoke penalty?

[justsomeguy]

I played today, and my playing partner was just about to tee off. After addressing the ball, and starting his backswing, a gust of wind moved the ball off the tee, it fell off just as my partner was 1/2 way through his downswing. He could not stop his swing, and continued to swing at the ball, which he hit. The thing is, the ball was still moving (after just having fallen off the tee) when he hit it. He actually made good contact and hit it in the fairway.
What is the rule in stroke play? 1 stoke penalty?

No penalty. Play it as it lies.

[AAA]

18-2 b. Ball Moving After Address
If a player's ball in playmoves after he has addressed it (other than as a result of a stroke), the player is deemed to have moved the ball and incurs a penalty of one stroke. The ball must be replaced, unless the movement of the ball occurs after the player has begun the stroke or the backward movement of the club for the stroke and the stroke is made.

[goochy]

I may be mistaken but surely if it is on the tee it is not a "ball in play"....doesn't it only become a ball in ball after he has made a stroke on from the tee box

Therefore would the rule you stated be appropriate?

[goochy]

Just checked the R&A Website.

Rule 11.3 No penalty...play it as it lies