Gambling 3NT and jumps to slam

Playing with Sean Gannon in the second round of the A/X Swiss yesterday, the auction started:

Andre	North	Sean	South
--	Pass	3NT	Pass
6♣	6♥

Sean and I play the a 3NT opening opposite an unpassed hand shows a solid 7 card minor with at most 1 ace or king outside the suit. Over 6♥, Sean asked: "Do you have any agreement about this 6♥ bid?"

South: "..umm.."

Sean: "Well, if you have talked about this auction, you can have all the imps."

Dealer: N Vul: EW	North ♠ KTxxx ♥ KTxxxx ♦ - ♣ xx
Andre ♠ Qxxx ♥ A ♦ AKQTxxx ♣ J		Sean ♠ Jx ♥ - ♦ Jxxx ♣ AKQT9xx
	South ♠ Ax ♥ QJxxxx ♦ xx ♣ xxx

Sean bid 7♣, confident that I held both pointed aces with one of those suits probably running, and that was passed out! The defense could have taken the first 2 tricks in spades but got off to the wrong lead. Our teammates Alli Howard and Lee Bukstel reached a fairly normal 6♥X, down 2, so we won 18 imps instead of losing 11.

Anyway, Sean and I now have the agreement that if we pass 6♥ in this or a similar auction, we are showing first round control of their suit, sort of inviting partner to bid 7 and if we double, we deny first round control.

We wound up winning flight X with 146 VP on a 120 average.