Explaination of bidding
1D = well it is an opening hand
1S = what else
2S = three card support with ruffing value, raise directly.
2N = Inquiry,
3D = long diamonds, three card support
4C = slam try, spades are trumps, no heart control
4D = diamond cue-bid, must have heart control to show this
4N = RKCB, I could have bid 4H LAST TRAIN
5S = Two keycards plus spade queeen
6S = long diamonds should give us a play, but I am worried that heart control is Kx or that you have ACE of hearts and no ace of diamonds. It is not a sure thing.
I think actually a slam invite 4H bid by north would have been better than blast 4NT. On this hand, South would have accepted the slam try and used blackwood himself. Last train would avoid the problem of south having some ackward hands.