With only them vulnerable at matchpoints, my (new) partner dealt and opened one club. After a pass by opponent, I bid one diamond with the following: (s) 7 (h) KQ (d) KT98543 (c) KT3.
Partner bid 2NT (balanced, 18-19). I decided to try for slam with 4NT (quantitative). Counting my 11, we had only 29 high card points between us, but with seven diamonds, I added two points each for the two long diamonds (above 5), bringing the total to 33. (A pair needs about 31 to be even money for a small slam.)
Partner took my bid for Blackwood, and bid 5 clubs, showing four aces. I took that as a sign off bid at 5 clubs, with one major suit unguarded, and figured that with three card support, clubs would be a good place. But I now believe that I should have continued in diamonds, since I had seven, and partner at least two.
We went down at five clubs (partner had a 4-4-2-3 distribution with all four aces and the queen of spades). We would have made six diamonds or six no trump.
Was I right to try for slam with my holding? Did I do so the right way or did partner reasonably take my 4NT bid for something other than quantitative? And should I at least have "pulled" five clubs to five diamonds?