The undisputed bridge expert Mr. Marty Bergen came to the conclusion that surrendering the 2 Club bid as being a natural bid would be a small sacrifice to pay, then surrendering the 2 Diamond bid also would be a small sacrifice in order to allow the responder to describe his hand more accurately.
Mr. Marty Bergen concluded that a 2 Club response by his partner, who is already a passed hand, could show a 3-card support for the opening Major suit with 10-12 points, and that a 2 Diamond response by his partner, who is already a passed hand, could show a 4-card support for the opening Major suit with 10-12 points. Although this seems immaterial at first, let us take two examples to show the difference and importance of this form of auction.
74 AQ9 854 KJ875
74 AQ95 85 KJ875
West North East South Meaning Pass Pass Pass 1 Pass 2 Promises a 3-card Heart support and 10-12 points.
West North East South Meaning Pass Pass Pass 1 Pass 2 Promises a 4-card Heart support and 10-12 points.
With the first holding, Mr. Marty Bergen suggests bidding 2 Clubs to indicate 3-card support after the bid of 1 Heart by his partner.
With the second holding, Mr. Marty Bergen suggests bidding 2 Diamonds to indicate 4-card support after the bid of 1 Heart by the opener.
Upon examining the two hands, one concludes that Hand 1 has one more Losing Tricks than Hand 2, which could mean the difference between a part-score and game. With this additional information, the opener has a better chance to reach game, knowing that there is a 9-card trump suit instead of an 8-card trump suit.
All continuances are a matter of partnership agreement.
Although the original version of the Drury convention as devised by Mr. Douglas Drury has undergone modifications, it is up to the partnership to conclude which form of the Drury convention it wishes to play. Whichever modification the partnership chooses to include in their bidding process, it should be included also in their individual partnership agreement.
This is why the Partnership Agreement is so important.