(1) East-West were playing a strong club system, so initially 2+ diamonds
(2) Now showing at least 5-5 in the minors and 14-15 points
This deal is from an imp pairs event at Mike Bell's Bridge Club.
West led a trump. Nicholas Greer, declarer, drew trumps in two rounds and played a diamond. West won and played a diamond back. Now a club from dummy was won by East with the king, East played another club won by West who played the king of hearts. Nicholas won this in dummy with the ace and eliminated the clubs by ruffing the third round. Now a heart left the defence with an intractable problem. If West was allowed to win with the ten he had to concede a ruff and discard, whereas if East overtook the ten with the queen dummy's jack would score a trick.
It is quite difficulty for the defence to foresee this end position. They missed a couple of chances. When in with the ace of diamonds West could have switched to the heart king or East had to switch to a heart when he won the king of clubs.
Thanks to Nicholas Greer for reporting this deal