Clearly West's 1NT was a bit unsound, but I wasn't to know that!
Seeing as I couldn't lead my partner's ♦, my obvious lead was K♣ - although I had little hope of running them - surely my partner would be void or singleton!
Partner failed to overtake my K (a slip-up for which she later apologised, to give her credit). Winning the A on round 2, she ventured K♦; declarer ducked the first round, took the marked finesse, and all was over....
Question, would I have given us a better chance by leading the Jack from KQJxxxx? A blatant false-card, yes, but then partner, "knowing" that I can't possibly have the Q, might play me for KJ10xxx and would obviously go up with the A and then return a ♣ through "declarer's Q"...
Or alternatively, should I have bid my ♣? At that vulnerability and void in partner's suit, I decided not to.
If only....