Not much blame to go around. 1
♦ is clearly correct: double is being a result merchant. The hand isn't good enough to double and bid diamonds, and we do have a good 6 card suit. We intend, if the bidding is low enough, to double at our next turn.
1N is not a weakness bid opposite an overcall, and the stiff diamond, altho an honour, calls for conservatism. If 1
♥ would have been a one round force, then there is some merit to the call, altho in NA at least the call is usually played as 5+ hearts. If it is NF, as is common, then it is dangerous since partner may pass us with a poor hand and, say, Qx in hearts.
Over 3
♣, I suspect that most BBF'ers play double as takeout, but once partner bids 1N, I think double should be more optional than anything else, and the void argues against suggesting we defend at all. 3
♦ seems middle of the road to me...it shows a good long suit and extra values. I don't think double is horrible, but I do think it is a bad idea. As S it wouldn't occur to me to pull, since partner is typically 3=3=6=1, with an opening hand.
S could now try 3
♥ over 3
♦, I suppose, en route to 3N, provided that partner understands that this is natural with extras. It is a bit of any overbid, since on some hands on which 3N makes, partner would have bid it himself....but we do have 2 Aces, and that diamond J is growing up.
I'd be very pleased with our efforts if any regular partner and I reached 4
♥ here.
Of course, this thread will be filled with people for whom reaching 4
♥ is a snap. I'm always amazed at how accurate some players are when they see both hands
'one of the great markers of the advance of human kindness is the howls you will hear from the Men of God' Johann Hari