Image copyright Getty Images Image caption Prince Charles takes a drink of whisky from a Quaich during the 2005 Mey Games

Theresa May will present Donald Trump with a traditional Scottish cup of friendship when she meets him in the White House on Friday.

The gift of an engraved quaich reflects the US President's Scottish ancestry, as the son of Mary Anne MacLeod from the Isle of Lewis.

The two-handled drinking bowls have been exchanged by Highland clan chiefs for centuries.

It is a token of hospitality and a symbol of kinship.

The cup's two handles are intended to signify trust on the part of the giver and the receiver.

Image copyright PA Image caption Theresa May will say the UK and US are unique partners

The prime minister will also present First Lady Melania Trump with a hamper of produce from her country residence Chequers, including apple juice, damson jam and marmalade, as well as Bakewell tarts and cranberry and white chocolate "shorties".

Mrs May will be the first world leader to hold face-to-face talks with President Trump in the White House.

Post-Brexit trade opportunities, security and intelligence co-operation and the future of Nato are likely to feature significantly in the talks.

Mrs May has said her goal is to build on the historic relationship between the two nations, underpinned by their shared values and common interests.

But she has said she "won't be afraid" to speak candidly to Mr Trump on matters where they disagree, having criticised remarks the businessman has made in the past about women and Muslims.

What is a Quaich?

The shallow, one or two-handed wooden bowls were traditionally used in Scotland from the 17th Century as drinking cups.

The English and US colonial versions were called porringers, while northern Sweden had its kuksa.

Now Scottish quaichs are most commonly made from silver and handed out as competition prizes or gifts.

Fishermen also use them to toast the opening of the new salmon season every year by tipping whisky from the quaich into the river.

Image copyright Paul Hodgkiss Designs Image caption The wooden quaichs were presented to every medallist at the 2014 Commonwealth Games in Glasgow

They have come to symbolise love and friendship and were used at the 2014 Commonwealth Games in Glasgow to promote that message.

A special commemorative quaich was presented to every medal winner, along with their gold, silver or bronze.

Designer Paul Hodgkiss said the a quaich was an ideal symbol of Scottish hospitality.

Image copyright Jeff J Mitchell Image caption Sir Walter Scott's Waterloo Tree Quaich is a famous and valuable item

One of the most famous quaichs is the Waterloo Tree Quaich, which is in the home of great Scottish writer Sir Walter Scott.

The rare piece is made from silver gilt and elm wood that was cut from a tree at the Waterloo battlefield.

The Duke of Wellington directed his troops from a position under the tree in 1815 and it subsequently became a target for souvenir hunters.

The quaich dates from 1824 and was made by Joseph Angell of London.

It is engraved with Scott's motto, "Watch Well".

Roddy Martine, editor of Scotch whisky industry magazine the Keeper of the Quaich, said it was not important that President Trump was teetotal.

He said the quaich was a gesture of friendship and did not need to be used for drinking whisky.

"It is a loving cup," he said.

"They began to formalise in the 17th Century. Highlanders could carry them around attached to their belts or they could put them in their sporran.

"It is a communal cup essentially. People didn't have glasses or tumblers in those days. They all drank out of the same cup."

He said: "You can drink anything out of a quaich. It is basically to carry liquid. It doesn't have to be whisky."

Mr Martine added: "It is a very canny gift, reflecting Mr Trump's Scottish heritage."