Unlike most at the club, we are not slaves to Blackwood. As it happens it made little difference on the two slammish hands we held, but I thought we bid them reasonably well:
We play 2/1, so LotG's two diamonds enabled me to bid a forcing two spades. Her three spades bid showed some slam interest but she was slightly confused by my diamond cue bid. Generally, which really means always, we show first round controls before second but would not cue bid shortage in partner's suit. So while I would cue bid the king, it should mean that I do not have a rounded ace, so signing off seems right.
Generally the time to cue bid a second-round control is when you have a stronger than expected trump holding, and the cue makes it easier for partner to show her controls. In this specific case, I was always bidding slam after the three spades bid and was just trying to find the right one.
LotG spent some time thinking over five hearts, trying to decide whether six notrump was the better contract. Perhaps the jack of diamonds would have been sufficient, but even with the lead through the clubs six spades was still looking a 50% contract at worst.
All but two tables bid the slam.
Two rounds later we picked up:
LotG showed a very strong hand with our sequence and the real question is whether I am obliged to cue bid. I believe that with a single ace, very poor trumps and no fit, in addition to a sequence that has described my hand well, I had no interest in helping towards a slam. Certainly LotG felt that I would always cue bid with two aces so we stopped at the safest level.
Four pairs matched us, another four stopped safely if five spades and only one tried the slam - unfortunately the hand on lead had both aces.