Stumble at the final hurdle

Well, that’s what should have happened.
At the table, West simply bid 7NT over 5 for -50 on the ♠J lead.

After South followed to three spades and two diamonds, there was a good case for hooking the heart but I didn’t. Sigh.

7NT would be preferred if East did not have the J but the second round of DCB would have located that easily.