Serious 3NT and Last Train: Slam Tries After a Major Fit

Serious 3NT is an artificial 3NT bid, made after a major-suit fit is agreed at the three level in a game-forcing auction, that shows real slam interest. It asks partner to start cue bidding. If you skip 3NT and cue bid at once, you show a mild slam try, and if you bid four of the major, you have no interest at all.

Last Train is the other tool for the same auctions: the bid just below four of the agreed major says "I still have some slam interest" without promising a control in the suit you bid. Together they help you stop in game when both hands are minimum, and look for slam only when one of you has something extra. Both come up all the time in 2/1 Game Force, so this article uses 2/1 auctions.

3NT is artificial only when all of these hold:

1. The auction is game forcing, for example after a 2/1 response such as 1♠ - 2♣.
2. A major-suit fit is agreed at the three level, so four of the major is still available.
3. Notrump no longer makes sense as a contract, because the side has found its eight-card or longer major fit.
4. Your partner has not yet limited his hand. If he has already shown a minimum, there is no point in telling him you are serious: you decide yourself.

The classic 2/1 auction is 1♠ - 2♣ - 2♠ - 3♠. Under the principle of fast arrival, responder's jump to 4♠ would show a minimum game force with no slam interest, so the slower 3♠ says "I could have more". Opener is the first player to speak after the fit, and his 3NT is serious.

After 1♠ - 2♣ - 2♠ - 3♠, opener has four kinds of bids:

The cue bids follow the usual style: show the cheapest first- or second-round control, and do not skip a cheaper suit in which you hold a control. A cue bid of 4♦ after 3NT therefore denies a club control. You can see what 3NT means in this auction in every system.

Frivolous (or non-serious) 3NT swaps the meanings: 3NT shows a mild slam try, and a direct cue bid shows a serious one. The argument for it is that the serious hand is the one more likely to need room, so it should start cue bidding at once, while the weaker hand gives away less information to the opening leader.

Both versions work. Serious 3NT is easier to remember, which is why many club partnerships choose it, while some strong partnerships prefer frivolous. Whatever you play, write it on your convention card: this is a classic source of disasters.

Last Train is the bid one step below four of the agreed major. With spades agreed, that bid is 4♥. With hearts agreed, it is 4♦. When the auction reaches that step, the bid says "I am still interested in slam, but I cannot go past game on my own". It says nothing about the suit named.

Why? Because it is the last bid that keeps game open. If you had a heart control and a slam interest, you would cue bid 4♥ anyway; if you have slam interest and no heart control, you have no other bid that shows interest below 4♠. Last Train covers both hands, and partner judges whether his cards fill the gap.

The convention was devised by Jeff Meckstroth, who named it after the Monkees song "Last Train to Clarksville". Without an agreement, most players read the bid as a natural cue bid, so discuss it first.

You are South with ♠AKJ853 ♥K4 ♦A73 ♣62, and partner holds ♠Q74 ♥862 ♦K5 ♣AKQ93. You open 1♠ and partner responds 2♣, game forcing in 2/1.

• 2♠: six spades, nothing more to say yet.
• 3♠: partner agrees spades and keeps slam open (4♠ would show no interest).
• 3NT: serious. With 15 HCP, six spades to the A-K and the ♦A, you want slam if partner has the right cards.
• 4♣: partner shows a club control.
• 4♦: you show the ♦A. You have no club control, but partner has already shown one, so you are not skipping anything.
• 4♥: Last Train. Partner still likes his hand, but he cannot bid a heart control: he has none. He bids the last step below 4♠.
• 4NT: your ♥K covers the heart suit as a second-round control, so you ask for key cards. Partner's 5♣ shows one or four: here one, the ♣A.
• 5♦: you hold four key cards between you; only the ♥A is missing. With one key card missing, you also need the trump queen, so 5♦ asks for it.
• 6♣: by a common agreement, partner shows the ♠Q and his cheapest side king, the ♣K.
• 6♠: one ace missing, no trump loser to fear. You bid the slam.

Without Last Train, partner would have had to choose between signing off in 4♠ and bidding past game with no heart control. Either choice can be wrong.

The same rules apply whenever the four conditions hold. A few common auctions:

• 1♥ - 2♣ - 2♥ - 3♥: hearts agreed below game. Opener's 3NT is serious; his 3♠ or four-level cue bids are not.
• 1♠ - 2♥ - 3♥: opener raises, responder is unlimited (with fast arrival, 4♥ by opener would show a minimum). Responder's 3NT is serious.
• 1♥ - 2♦ - 2♥ - 3♥: responder sets hearts at the three level. Opener speaks first, with 3NT, a cue bid or 4♥.

It does not apply after a non-forcing raise such as 1♠ - 2♠ - 3NT, where 3NT is a natural choice of games, or before a fit is agreed, as in 1♠ - 2♣ - 2♦ - 3NT, where 3NT is natural. After Jacoby 2NT many pairs have their own structure; agree whether serious 3NT applies there.

• Bidding serious 3NT with a minimum. It shows extras or excellent controls. A minimum with a control cue bids directly.
• Passing 3NT. In these auctions 3NT is forcing and artificial: partner is not offering to play there.
• Reading Last Train as a control. It promises interest, not a card in that suit. Before you bid slam, make sure that suit is covered.
• Forgetting the trump queen. When you finally ask with Roman Key Card Blackwood, the queen is part of the answer. Missing a key card and the queen, stay out of slam.

Practice these sequences in the Bidding Room with a robot partner, then compare with the wider methods in slam bidding, cue bids and splinter bids.