From the articleOriginating in the Highlands, where clan chiefs prized them as a token of hospitality, they have been used across Scotland for centuries as a cup of friendship.What do you give the man who (actually does) have everything? You give a symbol of friendship.Today it is rarely used as a drinking vessel, but rather it is a symbol of “welcome and kinship”.
Given that Mr. Trump is not (unless he were to buy it from the US government) entitled actually to personally retain a gift from a foreign leader, this sounds like an excellent choice by the British government.
Mr. Trump will do well if he finds an equally appropriate gift to exchange.
The fact remains that she is giving him an item used for drinking alcohol during Scottish history.
And it isn’t going unnoticed
For example
“It will hopefully delight the President, whose mother was from Scotland and who is proud of his tartan roots. The only trouble is that the 45th President of the US doesn’t drink alcohol. Never has.”
http://news.sky.com/story/mays-presents-to-trump-a-scottish-cup-and-jam-10742783