This is the Roberts of the popular imagination: brave explorer of the dangerous lands "beyond the Grand Tour". It was an image he encouraged, which helped the industry that sprang up after his return with the publication of his views of the Holy Land, but it wasn't entirely accurate. He was a constant traveller, but mostly he stayed within continental Europe. His one famous journey further afield lasted only nine months.
The 272 sketches, three books of drawings and a panorama of Cairo which Roberts brought back were, he acknowledged, "the materials that will serve me for the rest of my life". They served him well and provided fuel for the next 25 years. They were also the vehicle by which he completed his transformation from apprentice house painter and son of an Edinburgh shoemaker, to wealthy man about town, member of the Royal Academy and the Garrick Club.
In the ranks of the great artist travellers of the 19th century, Roberts comes across as a less endearing figure than the eccentric Edward Lear. Nevertheless, it is Roberts more than anyone else who provided the greatest topographical depictions of the ancient world. At times his finished oil paintings are a little too fabulous, a legacy from his days as a theatrical scene painter. He was, however, one of the greatest draughtsmen of his age and his watercolour sketches still offer one of the best glimpses of how the world used to look.
Scottish National Portrait Gallery, Queen St, Edinburgh (0131-556 8921) to 24 Nov