cistern

The auction doesn't make sense. 1S was bid (which should be natural), jumped to 4S with no sign of support in Spades from partner, yet didn't preempt or weak jump shift at all or open with apparently a motherload of Spades. I would pass 4S as partner, thinking partner must have AKQJT and nothing else.

I blame South. 1C > 2D usually shows 17+ points. Clearly, East and West have a big Spade fit, so it makes no sense for 4S to be natural (1S opener, 2S preempt or 1H> 1S could make 4S natural. With all this, North's desire to play in game, is in my opinion, perfectly understandable. 4S I take is an asking bid, asking partner to choose between Clubs and Diamonds (not hearts as N bid 4S). South should choose 5C, which makes easily enough. South's worst possible 16 HCP hand is JQ ♠ QJ ♥ AJ ♣ KQ ♦ Even opposite this hand, game would still be about 50/50.

Matchpoints, neither team vulnerable. N/S bid as follows: [hv=pc=n&s=sk8hq5daqt3ckt872&w=saj64hkj872dk6c93&n=sthat43d9754caq64&e=sq97532h96dj82cj5&d=n&v=0&b=1&a=pp1c1hd1s2d2s4sppp]399|300[/hv] Who do you blame for the bidding, N or S? Double dummy reveals that the best contract for N/S is 5c or 5d with South as declarer, which will always make with perfect play. E/W can make 1H or 3S at best.