A good book: On page 215 of Kit Woolsey’s First edition of “Matchpoints” and on page 218 of his recent Second edition, he states that when a pre-empt has been raised to one under opponents’ game and opponents go to game, “a pre-emptor who has been raised is allowed to violate his usual oath of silence and join in with a double or bid if his hand is exceptionally defensively or offensively (respectively) oriented for his pre-empt.”
The Bidding: East makes a not vulnerable weak two bid. The suit is a two-loser suit no matter what and the hand is very short in the majors. This is a perfect weak two bid with little defense.
South bids Three Hearts. Is this a further pre-empt? No, absolutely not. One does not pre-empt a pre-empt and one certainly does not cooperate with a pre-empting opponent.
South is showing a very strong suit and a hand that has around four losers. It is stronger than bidding Two Hearts.
West ups the ante and bids Four Diamonds. He probably should have four-card support, but he has three-card support and a void. Furthermore, his three Kings look very useful.
North asks for keycards and East raise his own pre-empt in an attempt to disrupt Blackwood. Yes, North and South will use D0P1, but Five Diamonds still takes away the Queen-ask. Furthermore, his hand is very offensively oriented and he suspects partner is short in Hearts.
South doubles for the first step which is zero or three keycards.
He passes for the second step, one or four keycards and he bids Five Hearts for the third step, two keycards without the Queen. Finally, he bids Five Spades for the fourth and last step, two keycards with the Queen of trump. Here the first step is fitting.
In an uncontested auction, North and South should be able to get to Seven Hearts, but in this contested auction they settle for a small slam. West has too much possible defense to save (to make a sacrifice) at the seven level.
The play: Declarer wins the opening Diamond lead, cashes the Club Ace and ruffs a Club. He cashes the Spade Ace because when East cannot overruff the dummy, he will discard his only Spade. Declarer then ruffs a Diamond and ruffs another Club. He ruffs the last diamond and then ruffs the last Club with the Ace. He ruffs a Spade back to his hand and draws trump. He makes Seven for +1460.