I thought I was dummy

Ted and I played the SBU pairs last Tuesday. We did well, finishing over 60%, but far from the lead. There were five or six hands where we got a bad score, all self-inflicted. There was one 4♠ where Ted left on seeing I had ten cashable tricks, then came back to see I had somehow gone one down.

The hand below is a more forgivable one:

Ted opened a Benji 2♣, showing a strong suit. My 2♦ was a relay, then he showed Diamonds. I bid a natural 3♠ and he repeated his Diamonds. My 5♣ I think at this stage must be a cuebid. Ted thought so too and bid 6♦.

After the ♥T lead I wrote "brb" and dashed off to make a cup of tea. When I came back the ♥T was still there and the Round Clock had gone negative. I'd forgotten that since I'd bid Diamonds first I was playing it.

The slam has excellent chances. Although slightly wary of the lead, I decided to play for a Heart ruff. I took the two top Hearts and lead a third. This was quickly ruffed by West. With a club still to lose I had no choice but to over-ruff with the ♦J. It now seemed unlikely I could get another Heart ruff, or set up the Spades, so I crossed to hand in Spades and lead a Club up. Luckily the ♣A was onside, and I might now have enough tricks (two Spades, three Hearts, six Diamonds and one Club).

However, I've already ruffed with the ♦J, so am at risk of losing a trump trick if they don't split 3-2. I lead a Spade back to dummy, and cashed the ♣K.

All that remained was to draw trumps. At this point I knew East started with five Hearts, likely two Spades (she dropped the ♠QJ with the ♠T on table), and maybe two Clubs (she played the ♣9 then ♣J under my King. If I trust all of this then I know she started with four Diamonds, so I can gloriously finesse and make the contract

However, I didn't finesse. I just played trumps from the top and went one off. A missed opportunity.