notproven

Partner's last bid ("you should have passed") is forcing to a new partner. The double was acceptable, but risky. Your bid of 3♠ was certainly reasonable. It didn't work out.

3♠. Since partner may have a long strong suit with extras outside (say 19 HCP and AKJ10xxx in clubs or hearts), pass is too much of a unilateral position. I do have sympathy for 3NT, because that rates to make as well if partner has that strong a hand. This is why players stretch to pre-empt: the opponents are often reduced to guessing because they have no clearcut action. But, if I knew the opponents (we don't in this example), I'd be more inclined to pass some joker who is known to be hyperactive.

Sorry Bigbenvic, you missed the point. In this auction, where east promises 2+♣, and the opponents surely have 10+♣, west can't have a club stack, and everybody at the table knows it. Therefore, in this auction west would never have a reason to double for penalties, given that he knows his side has 9+♠ and most of the points, and everybody at the table knows that, too. It's called situational bidding, where the meaning of a bid depends upon inferences taken from the rest of the bidding. In a different auction, where west is not known to be short, and a penalty double is a viable option, a cue bid would not be smart because it would be ambiguous. In the auction given, there is no ambiguity: west CANNOT be making a penalty double, ever.

On most 2/1 cards, a jump to 3♣ in competition is pre-emptive, not a fit showing jump (see the GIB 2/1 card). The club suit is so good and you have heart support, so game (or slam) is not out of the question, so you want to get a response from partner. (Playing that 3♣ is a fit showing jump here (special agreement) might not work out if partner expects a better ♥ suit). Playing the GIB 2/1 card, 2♣ is best because you do have more than 10 support points and a real suit, which is all the bid promises.

I believe west should have doubled 5 ♣. It must be a cue bid, and is almost certainly a void on this auction. West knows that east has at least 3 ♠ (because east accepted the transfer over interference). East, in turn, knows from his hand that west must have concentrated values in spades, and can therefore comfortably bid the spade slam.