Three of Richard and the kids, a single portrait of Joanne as a smiling young woman.

He was paid £200, "which was more," he wrote, "than any English artist ever received for a single portrait".

She needed eight minutes to expose the wet glass plate for a single portrait.

A single portrait, signed by Leopold Robert, shone in its carved and gilded frame.

But there is little scholarly agreement on a single portrait, or the methods needed to construct it.

Once again, Miss Burson has used a computer to combine different faces and facial features into single portraits.

A few are single portraits from the 1970's; one depicts a woman standing, resolute of coiffure and pose, in a neat black dress.

A single sitting can last for up to six hours (and a single portrait can take at least a year to finish).

Apart from the swords, a single portrait broke the monotony of the white walls.

So far, not a single portrait has been definitely shown to depict the toga, a key symbol of Roman citizenship.