North opened a weak no trump, and I doubled for penalty. South redoubled to show a 5 card suit. Partner then found the excellent bid of 4♥. I thought for a bit and decided that partner should have at least a solid 6 card heart suit, or a semi-solid 7+ suit. I checked for keycards with 4NT, and bid 6♥ when partner showed 2 keycards and the ♥Q.
The full hand was:
The best thing about this hand is I don't see how we could bid the slam without the weak 1NT opening from North.