First curse them for leading a club.. don't they know that against a grand slam you are suppose to lead a trump. On a trump lead, i could pull trumps, cash two hearts, ruff a heart, cross to club, ruff a heart, and presumably cross to diamond and cash long heart.
Now the cash heart, ruff heart needs 3-2 instead of 4-1 hearts. I am not sure i would play a spade at trick two. At least two other lines exist.
One is to play to ruff a
♦ in dummy. This is
♦K at trick two. Loses if you find diamonds 5-2. Playing for 4-3 diamonds is about 62%. That is better than relying on finesse in either major, or finding hearts divided 3-3 or 4-2 with doubleton queen or 5-1 with singleton Q which comes to 54% (3-3 is about 35.5%, 4-2 with Qx is 16%, and Q 2.5%).
However, you do have some combined changes.. You can take the 54% that the heart queen falls, and in the remaining time it does not, you can take the diamond finesse through WEST (54%+1/2*46%= 77%). So, no. It is not right to go for the immediate diamond finesse.
So the general play would be to play for hearts first, then if that fails, play for diamonds. There is also some squeeze chances (See below).
My line would have been.. to ruff a club at trick two, then pull trumps.. then cash two top hearts, then if no one had shown out of hearts, ruff a heart. If someone had a singleton heart that was not the Queen (or west with singleton TEN, when ruffing finessee works) I will ruff a second club to try to isolate a club threat.. (Btw, did east give a count signal i can read at trick one and two when I ruffed a club). Anyway, assume hearts are 4-2 and i ruffed one.. i now reach these combination of endings... (after 3-2 trump split.. if 4-1 i will have throw a club and played an extra round of trumps). Here I gave them both a club stopper despite my efforts to ruff one, and I gave them both the diamond queen (impossible in real world). First hand, EAST has four hearts, second WEST has four hearts..
S: 7S