Lord Molyb, on 2013-March-01, 14:06, said:
If opener had a 10 count surely he wouldn't bid 3NT?
Indeed he would not.
PhilKing, on 2013-March-01, 14:35, said:
3
♦ is a huge underbid, even if partner has a 10 count 100% of the time. I would bid 3
♣.
I would not sit for 3NT. We could be cold for slam with 3NT down.
♠x
♥Kxxxx
♦Kxxx
♣ATx is a decent slam and partner would pass 3
♦. Give him the red queens as well and we are down in 3NT. And don't tell me partner would not bid it with a stiff spade - I have seen it 100 times.
I will have to manufacture some sort of recovery shot now. 4
♣! If partner has 11 points, maybe he will cue 4
♠.

You are on the right track. Except that you seem to want partner to supply information to you, when instead you should be providing information to partner.
At the table, I bid 5
♦. But, as my partner pointed out, as long as I am going to bid 5
♦, how could it be wrong to cue bid the
♥A along the way? This is all partner needs, as his hand is:
J
Jxxxx
KQxx
AKT
He will bid 6
♦, which rolls in on a club lead, and which isn't difficult at all on a non-diamond lead. On a diamond lead, you will have to establish the hearts, or, if that doesn't work, take the club finesse.
This hand was a push at +420.