Partner's solution
As West my first choice would have been 4
♣ given the 3 vs 2 keycards status. Probabilities of a
♠ vs
♣ slam are ~5% vs ~60%
Partner had other ideas though and bid 4NT showing 2/4 keycards with
♠ as trumps.
I bypass the 5
♣ cue-bid given
♣ have been shown twice with 2 of the top 3 honours assumed. Bidding 5
♣ in this case will deny the 2 honours.
5
♠ sign-off is tempting as partner is likely to have only 2 keycards, but I bid 5
♦ showing the needed
♦ control, but with
♠ as trumps, wrong-siding & the single keycard there is a problem.
Partner, however has other ideas and knowing I have the Ace & Queen
♣ bids 6
♣ counting at least 4 keyacrds & Q
♣. I quickly pass not thinking about a possible 6
♠/ 6NT.
At other tables 1 pair bid and made 6
♠, 4x4
♠+2, 2x4
♠+1,1x4
♠,1x4
♠-1,3x5
♣+1 & a few odd/underbid final contracts.