[Ciel turns smartly on his heels, smoothly dipping into a returning bow and all the while coloring a little at being caught ogling such a contraption. Especially one that Constance seems to be familiar with. And why is that?! Isn't she from an era older than his?]
It's most welcome to see you as well. [Just not while he's floundering with thingamabobs?] You know what it is? And...how long ago was that, the first time you saw it in action?
[Just so he knows how much ire he needs to direct Sebastian's way for not telling him about this. For chances are, if Constance saw it in action, in this very hotel, then it's for certain that Sebastian very much knows about it.
And failed to inform Ciel.
And made him look the fool.
He wouldn't put it past that jerk to do this on purpose.]