THE stronger two-over-one change of suit response favoured by modern Acol has affected opener’s rebid.
Because responder promises 10+ points any rebid that shows extra values makes the auction forcing to game. After 1H-2D a 2NT rebid, or a jump to 3H, or a reverse into 2S are all game-forcing. The 2NT rebid is made with any balanced hand too strong to open 1NT, not strong enough for 2NT – therefore a wide-ranging 15-19 points. There is no need to jump to 3NT with a balanced hand, and this gives more space to investigate the best game.
Many players are reluctant to rebid 2NT with a hand like South’s, concerned about the weakness in diamonds. But the forcing 2NT rebid does not commit the partnership to playing in no-trump, and the bid is the most descriptive available. Here North has a minimum two-over-one response, but he should still explore alternative contracts. His 3H rebid shows three-card support (with 4 hearts he should raise immediately), and here simply offers a choice of game. With only four hearts South has a choice of rebid: 3S shows 4-4 in the majors, in case partner is 4-3-1-5; and 3NT shows a balanced hand without four spades.
Here South is happy to play in the 5-3 heart fit. North’s 3H bid does not limit his hand, so South makes a courtesy cuebid of 4C in case partner has some slam interest.
Bidding beyond 3NT means that he has chosen to play in hearts, and North signs off with his minimum.