Hi ,
I am familiar with these and yes they are 18thc , though I would date them nearer 1780 simply because of the polished pontils , I have seen them with snapped pontils too ,the 1 sold by Bonhams was from the Hubbard Collection ,a collection I know very well , the pair up north I have also seen and they are also ok , I think the may well have been made for a Scottish hunting lodge or similar ,the fact that a few have turned up recently is nothing to worry about , sometimes it's the case that 1 is seen and prompts another owners to sell , so like buses a few come along fairly soon ,
cheers ,
Peter.
my pair below .