I bought this large lidded tankard with possible a christening inscription
The lid only has the makers marks
Any thoughts
The hallmark is clear enough, London 1766:
Christening gift? Possible, but rather unusual. The more traditional gift would be a small mug, about one-quarter the size of this bruiser. And christening gifts typically had an inscription that was a bit more detailed. I’ve got one, for example, that reads, “Douglas Guillaume Cave from his Godfather Francis Hundley 1841.” And another from 1811: “Mary Lyall The Gift of Her GRANDMOTHER Mary Bagster.”
Since we have only a name and a date, it could be a gift for almost any occasion, or even just a piece whose owner wanted to lay claim to it in an unmistakable manner. Then again, maybe it was just a very large baby. 
ETA: The makers are clearly William and James Priest:
And it looks to be in very good condition - it should clean up nicely. 
On the other hand the nomenclature “Godfather” does rather indicate baptism, no?
I got one made by Jonathan Swift a decade later from my grandfather celebrating a birth and christening exactly a month later than either event occurred both on the mug’s inscription and in the church records. He was also the priest performing the rite.
His daughter, my mother was WRNS boats crew in Plymouth (HMNB Devonport) during the war and she had been retrieved from there by Litchfield the local bishop, and a friend, to become a respectable married lady in a Shropshire that A E Housman would have recognized.
So why did beer mugs have lids? If you’ve ever tried drinking out of one, the lid keep getting in the way of a good quaff. So there must be some over-riding practical reason.
And is the cleft in the lower part of the handle really a whistle to blow for a refill?
And where were these mugs employed? In the local ale houses or in a domestic setting?
And why did some of them later have glass bottoms?
And who invented them, the Germans or the English or neither?
And why do so many turn up today with later added spouts?
CRWW
I’ve seen a few of those. Vandalism.
Yes it destroys value. But also re-purposing rather than deliberate destruction? Victorians opposed to drinking alcohol once Dr Snow discovered there were other ways of preventing disease from liquids other than distillation?
CRWW
Thanks
And the lid only have the makers mark?
You know the Victorian motto: “Everything goes better with some repoussé.”
I would be concerned about that only if it were a different maker. Lids often get short shrift, sometimes with only the lion passant or only a repetition of the maker’s mark.