Hallmarked Georgian Silver Vinaigrette

A very fine Georgian hallmarked silver vinaigrette with silver gilt interior. It has three marks, Georgian head, manufacturer initials 'ib' (various named manufacturer could be, John Booth, John Bridge, John Boland or John Byrne). The lid has a vacant cartouche. There appears to be no date letter showing anywhere. The inner silver gilt grill opens to reveal the remains of possibly the original sponge. Measuring 38mm wide x 27mm it would have fitted perfectly into a gentleman's waistcoat pocket. Other than a couple of tiny dings to the rear I see nothing to cause concern.