'The most interesting questions from visitors to the Dutch sister site (Bridgevaria.nl)'. 

Dear Ed & Peter,

I am inclined to bid rather aggressively, so it's just as well that my partner tends to apply the brakes. This deal is from match point play at our club.

Z/Allen		♠	9
		♥	K 9 4
		♦	A 7 6 4
		♣	A J 7 6 3
♠	8 7 6 4 3			♠	K Q 2
♥	A 10			♥	6
♦	J 5 2			♦	K 10 9 8 3
♣	Q 10 2			♣	K 9 8 4
		♠	A J 10 5
		♥	Q J 8 7 5 3 2
		♦	Q
		♣	5

 Dear Ed Hoogenkamp (South)

Dear Klaas,

Firstly I am glad to read that your partner, given the fact that you like to bid aggressively, tends to apply the brakes. A balance in the partnership is important.
Next to your question: is this 1♠ overcall punishable or reprehensible?
Punishable: no; you are allowed to bid what you like.
Reprehensible? In the long run West will much more often obtain a bad result than a good one. His partner will lead the suit if the opponents end up playing the contract; given the quality of his spade suit, that lead will usually turn out to be the wrong one. Or partner may support spades, for instance as a save. So I wouldn't recommend an overcall like this.
Now and then, however, it will be successful, like in this case, with you as the victim.
That is to say... you were so convinced that West had the ♠Q, that you lost your concentration.
After West had (wrongly!) ducked the ♥A (trump ace), your trump continuation was pointless. After all, the trump ace was the only trump still out with EW.
Before committing yourself to the spade decision, you could have tried another chance first (without giving up upon the spade chance): don't play that second trump; instead play the ♣A, ruff a club, cross to the ♦A and ruff another club. It shows that the club suit is 4-3, so you can set up the fifth one by another ruff. On that club you can pitch your small spade. The contract is now 100%: ruff the ♠5, ruff another club and ruff the ♠10. The fact that the ♠Q tumbles, is nice but irrelevant: after all you are in dummy now and pitch your last spade, the ♠J, on the master club.
True, this is a typical 'comfy chair analysis'; at the table you thought the slam was in the bag and didn't think any further ('what if East has the ♠Q after all?'). Bad luck!

Let's see what Peter has to say about the overcall; I think in Norway this spade suit is a trifle too good for a simple overcall...

Un saludo, greetings from Barcelona

Answer Peter van der Linden (North)

Dear Klaas,

Brace yourself, I have some nuts to crack.

About your dummy play: Ed explains reasonably well (yes, the heat has receded somewhat in Barcelona) how you could have played better.
But only reasonably well, since by touching trumps too early, you should always have been defeated. And what's more: if West would have had the ♠Q, you would have been defeated as well, the way you played!
I'll explain: you have to get rid of three spades, since you have the trump ace to lose. The moment you played trumps, West should have gone up and played back his second trump (you were lucky he didn't lead the ♥A and another heart!). Your pointless second round of trumps put you in that same, fatal situation: only one trump left in dummy and not enough entries to ruff out the clubs. Now suppose West had covered your ♠J with the ♠Q: you would have had to ruff with dummy's last trump and would have been stuck with an inescapable loser: the ♠5! So the misleading (?) overcall had nothing to do with your defeat, you misplayed the hand... (West's mistake of ducking the first trump trick, offered you a new chance: the line of play Ed pointed out).
Then how should you have played?
- Setting up the clubs doesn't work against good defence, just try it. You cannot draw the small trumps without giving EW the opportunity of removing the ♦A, necessary as an entry for the master club. (In Ed's line of play, setting up the club did succeed only because of West's severe mistake of ducking the trump trick.)
- What about not drawing trumps and taking an immediate ruffing finesse against the ♠Q? Suppose West has that card, I agree it is fair to expect so. If West doesn't cover, the ♠J wins. You next ruff the ♠5 and play the ♥Q. If West wins and plays a fourth spade you ruff with dummy's ♥K. No problem.
But what if West covers the ♠J (and he should do so)? Dummy ruffs, you ruff a minor and ruff the ♠5. Dummy has the bare ♥K left. If you play a trump now, West will win and play a spade. Admitted, you do make your contract, since unexpectedly East had the singleton trump. But the feeling isn't right.
- To me the logical line of play looks to be: try to ruff all three spades in dummy. All you need is that East either has three spades (a fair chance since West hasn't jumped to 2♠) or doesn't have the ♥10. This line of play would have been successful.

Still your question remains about whether such an overcall is allowed (my words). Ed states, correctly, that West's overcall is neither punishable nor reprehensible. Regarding the latter he points out that such an overcall is not sensible (which indeed it is not, unless you play Ed).
From your question, however, I take it that you mean to ask whether such an overcall is decent towards the opponents.

Situations like these often lead to heated discussions. There is more or less general agreement about the following: if a partnership has bidding habits or bidding agreements that deviate from what is considered standard, it should warn the opponents by inserting these habits and agreements on the convention card and alert the bids in question.
If EW usually or even regularly overcall on hands like West's, this should be filed on the convention card and East should alert West's overcall. After all, East should not have any information ('my partner overcalls on about any five card suit') which the opponents have not, that would be breaching the principle of full disclosure.
Having said that, I have to put this somewhat into perspective, since one might ask: is West's overcall deviating so much that filing on the convention card and alerting are required? Opinions will differ about this, I think. So this is a matter for directors.

I add that many pairs who make overcalls (or other deviating bids) like this, afterwards often state that it was exceptional: 'He normally doesn't make overcalls like that!' I tend to take this with a pinch of salt: usually the partner of the bidder who deviates knows perfectly well that his partner does this regularly.
Often such a 'non-alerter who knows' gives himself away by his reaction to his partner's bid. When we look at your case, East's pass over 3♥ is telling. Why didn't he do the normal thing and support spades, having three card support, 11HCP and ruffing value in hearts? (I make an exception for very inexperienced or bad players; they may pass because they are not skilled enough. But if EW are experienced and reasonably skilled players, East's non-alerting in your deal is at least questionable, I would say).  

To sum it up, my personal view is that:
1. West's overcall is not reprehensible if he usually doesn't make overcalls like this. His deviation is incidental then and that is most certainly allowed. His partner neither knows about nor reckons with the deviation and bids as if West's overcall is a standard one.
2. West's overcall is not reprehensible either if such overcalls are more or less common in his partnership but in that case East's failure to alert is reprehensible and even punishable!
This is not the end of it. If West ends up being declarer or dummy, he should alert the opponents about his own non-standard bid immediately after the last pass. In not doing so, West is reprehensible and punishable after all.

You didn't ask for it, but I'd like to comment on your opening sentence: 'I am inclined to bid rather aggressively, so it's just as well that my partner tends to apply the breaks.' Quite an understatement in view of the bidding of you and your partner on the given deal!
I think you and partner are overdoing things: your aggressive bidding is really over the top and your partner's bidding is far too timid (I guess his braking produces deep skid marks on the table!).
First your partner: it is hard to imagine that he settles for an invitational 3♥ bid over your 1♥ opening (which obviously shows a five-card suit). He has 12 HCP plus two distributional points for the singleton spade). Furthermore these are high quality HCP: two aces and the trump king. In short: opposite even the worst minimum in your hand, he should want to be in game.

You're next: you are lacking three aces and the trump king and should be worried about the second round of spades. Still you roll out Old Black opposite a partner who has announced 10-11 points (distributional points included!). 6♥ is only on if partner has two aces and the trump king and a singleton spade* — all of which he cannot have but still has...
(* Exception: the ♥A, a minor suit ace and a singleton spade can suffice, but then the finesse for the ♥K must succeed and dummy must ruff three spades, meaning he must have a lot of trumps...).

On a bad day partner will — correctly! — bid 3♥ on: