Tricky slam

This fascinating hand came up at the Woodberry last night

West opens a weak 2 hearts.  How many spades do you bid as North?  I think 3S (strong jump overcall) is just right but I can understand 4S.  2S seems wrong to me as you do have a very powerful hand which a simple overcall doesn't describe but it might work well if you get another chance later.

At my table the auction went 2H-4S-5H.  Now the obvious action for me at this vulnerability is to double but it seemed likely to me that East would have a running club suit and if someone is void in spades we might not get enough compensation.  Meanwhile if partner has diamond values we could easily be making +510 vs +500 or +980 vs +800 in spades.  I decided to bid 6S which was right in theory but wrong in practice as it takes a precise series of plays to make 6S (which was doubled by East).

After a club lead you ruff, ruff a heart, ruff a club, play the queen of hearts covered and ruffed (only Jx of hearts in East gives you a chance).   Then play a trump to dummy, ten of hearts covered and ruffed and lead a diamond towards the jack.  Now you make if East has KQ(xx) of diamonds as he will have to give a ruff and discard or else lead away from their remaining royal allowing you to score the jack of diamonds.  East ducking is no better of course.  Either way you will not only have an extra trick you will also have an extra dummy entry to cash the winning heart.  

The alternative at the critical moment would be to play ace and a diamond winning if West has a stiff diamond honour but on the bidding I think the first line is indicated.

In practice my partner went one down and some declarers only made 10 tricks in spades which is hard to explain.  Sarah Bell was the only one to make 12 tricks in 5S but that was only slightly above average as others were making 4S and 5S doubled.  Doubling 5H would have been good enough for a joint top.