The origin of this convention is unknown and is properly designated as the Thomas Four Diamonds convention. It can be used in several bidding systems, such as the Universal Club bidding system as developed by Mr. Fred R. Thomas, for whom the method is named, but can also be employed as a stand-alone method of asking for Aces. The convention is used only used after an opening of a Major suit, not after a Minor suit opening.
Note: In the Universal Club bidding system the Thomas conventional method of Ace-asking may also be employed following a 2 Diamonds opening, which shows a three-suited holding, possibly a two-suited holding, with a range between 16 and 21 high card points.
The conventional method is initiated by a jump by responder to 4 Diamonds following an opening bid by partner in a Major suit. The responses and the meanings are shown in the outline below.
Ace Asking
The guideline states that once the Thomas Ace-Asking bid has been initiated, then a response by the opener in the Major suit opened does not indicate any desire to sign off. The response to the Thomas Ace-Asking bid, even if it is the suit of the opener, only shows the number of Aces held. The Thomas Ace-Asking bid does not include the King of trump, or any Keycard-style responses.
An example clarifies the initiation of the Thomas Ace-asking convention:
| North |
|
South |
|
Meaning |
|
|
|
|
|
1  |
|
4  |
|
The responder initiates the Thomas Ace-asking bid as the first response. This response indicates a strong interest in slam. |
| 4 NT |
|
|
|
The opener shows two Aces. |
King Asking
The responder can also ask for the number of Kings once the responder has determined that the partnership holds all four Aces. To initiate the King-Asking bid the responder bids 5 Clubs.
Note: Since a bid of 5 Clubs by the responder shows four Aces, then the responder is unable to employ this bid when attempting to establish the number of Kings. In this perhaps rare instance that the opener holds all four Aces, and the responder wishes to know the number of held Kings, then the responder must bid 5 Diamonds. In this instance all bids by the opener are pushed up one rank.
The responses to a King-Asking bid are shown below:
| Opener |
|
Responder |
|
Meaning |
4  //NT |
|
5  |
|
The responder initiates the King-asking bid following the determination of the number of Aces. |
| 5 |
|
|
|
Shows 0 or 4 Kings. |
| 5 |
|
|
|
Shows 1 King. |
| 5 |
|
|
|
Shows 2 Kings. |
| 5 NT |
|
|
|
Shows 3 Kings. |
Employing the example as above, the continuation would evolve as follows:
| North |
|
South |
|
Meaning |
|
|
|
|
|
| 1 |
|
4 |
|
The responder initiates the Thomas Ace-asking bid as the first response. This response indicates a strong interest in slam. |
| 4 NT |
|
|
|
The opener shows two Aces. |
| |
|
5 |
|
The responder initiates the King-Asking feature. |
| 5 |
|
|
|
The opener shows two Kings. |
| |
|
6 |
|
Since one King is missing and the values do not translate into a grand slam, the responder bids the small slam. |
King-Asking Bid When Ace-Asking Response is 5 Clubs
In the case that the first response to an Ace-asking 4 Diamonds bid is 5 Clubs, showing all 4 Aces, then the bidding sequence for King-asking is increased by one rank, which is outlined in the schematic below.
| Opener |
|
Responder |
|
Meaning |
| 1 / |
|
4 |
|
The responder initiates the King-asking bid following the determination that opener holds. |
| 5 |
|
|
|
Showing 4 Aces. |
|
|
5 |
|
King-asking bid, but only if the opener holds all four Aces. |
| 5 |
|
|
|
Shows 0 or 4 Kings. |
| 5 |
|
|
|
Shows 1 King. |
| 5 NT |
|
|
|
Shows 2 Kings. |
| 6 |
|
|
|
Shows 3 Kings. |
If you wish to include this feature, or any other feature, of the game of bridge in your partnership agreement, then please make certain that the concept is understood by both partners. Be aware whether or not the feature is alertable or not and whether an announcement should or must be made. Check with the governing body and/or the bridge district and/or the bridge unit prior to the game to establish the guidelines applied. Please include the particular feature on your convention card in order that your opponents are also aware of this feature during the bidding process, since this information must be made known to them according to the Laws of Duplicate Contract Bridge. We do not always include the procedure regarding Alerts and/or Announcements, since these regulations are changed and revised during time by the governing body. It is our intention only to present the information as concisely and as accurately as possible.