With South as dealer, and an unbalanced 20 points, I imagine most players would open 1C (longest suit). West has nothing to say, and now North can bid 1S. This is generally preferable to raising a minor suit even with four, as it enables partner to better describe their hand. With 10 Losing Trick Count partner could be unhappy to hear any raise higher than 2C.

South now can start to advise partner on strength and shape. 2D is a “Reverse” forcing partner to prefer your first bid suit at the 3 level thus showing strength – at least a good 16 points. With just an Ace and three Jacks, North will simply bid 3C. 

South with a known 20+6 points will still look for game – but where? Bidding 3S now will get the complete shape and strength over to partner. Having already shown 16+ points, and “settled” in a club part score, this 3S bid must surely show 19-21 points and precisely 3S. (If south had 4, an immediate raise of 1S would have occurred, and if the clubs and diamonds were equal length, South would have opened 1D). South has therefore told us of his 3-1-4-5 shape and his massive point count.

North will not relish playing a spade contract with such weak spades, and with nothing in hearts, will not want to be in 3NT, but 4C is quite comfortable. South will look at his four LTC hand and raise to 5C.

This will be easily made losing just a heart and a club – so a top for N/S? Four pairs ended up in 3NT, 2 by north and 2 by South. Having heard the bidding these should be defeated by taking six heart tricks -but no – they all made it!

E/W heard the bidding and ignored it. As defenders you will find the best opening lead by listening to the information provided by the declaring side and taking full advantage. Even if you don’t participate in the bidding – do listen to it – it will help your defence.