A rare coin struck to commemorate the marriage of Mary, Queen of Scots and Lord Darnley has gone on display.

It is one of only two such coins of its type in existence.

They were intended for general circulation but were withdrawn soon after minting.

I cannot overestimate the importance of the addition to our collection Nick Holmes NMS

In 1565 Mary married her cousin Henry Stuart, Lord Darnley, an English nobleman.

Their only child was to become James VI (James I of England).

The coin has been bought by the National Museums of Scotland (NMS) with money from the Heritage Lottery Fund.

It will be displayed in the Museum of Scotland in Edinburgh.

An anonymous donor from the US also helped fund the purchase.

Nick Holmes, curator of numismatics at NMS, said: "I cannot overestimate the importance of the addition to our collection.

"The life of Mary Queen of Scots is one of the most famous and popular periods of Scotland's history."