Adeline Amar, an assistant at the Scottish National Gallery of Modern Art in Edinburgh, compares a real life Picasso, newly purchased for the nation, with a photograph of a work from a book.

The artwork, entitled Head, which dates back to 1912, has gone on display for the first time after being acquired by the gallery from Sotheby's for £631,000.

The cubist Picasso drawing was bought with a donation left by art collectors, Edinburgh University professor Henry Walton and wife Dr Sula Wolff. Picture: Stewart Attwood