Negative Doubles

Board 5
North Deals
N-S Vul
♠10
♥K 9 7 4
♦K J 9 8 7 2
♣A 4
♠J 8 7 6 5
♥A J 5 3
♦—
♣J 8 6 3
N
WE
S
♠A K Q 4 3
♥Q
♦Q 10 6 5
♣K 5 2
♠9 2
♥10 8 6 2
♦A 4 3
♣Q 10 9 7
WestNorthEastSouth
 1♦11♠2Dbl3
3♠4Pass4♠All pass
  1. N opens 1♦
  2. E overcalls 1♠
  3. S uses a negative double showing ♥
  4. W has an easy competitive raise. A grateful E happily bids to game.
4♠ by East