This is the 4th Duke of Portland (1768 -1854). He held the title Marquess of Titchfield from birth until 1795. He married the Scottish heiress, Henrietta Scott who had come into the ownership of the Kilmarnock estate which had been the ancestral home of the Boyd family, Lords of Kilmarnock since the middle ages. When the estate became part of the Portland properties, the 4th Duke incorporated the name Scott into his own becoming - William Cavendish-Scott-Bentink.
The Duke developed the harbour at Troon and the railway from Kilmarnock to transport the coal from deposits on the estate.
He had an active political career serving in the governments of George Canning and Lord Goderich.
This is a typical example of James Faed's mezzotint engravings for which he was renowned in his lifetime. However, like his brothers John and Thomas, he was also a skilled landscape artist, portrait painter and miniaturist.
According to his own records, James engraved 133 plates in the 50 year period between 1849 and 1898. The majortity of his engravings were of portraits of prominent figures like the Duke of Portland, whose original oil portrait was painted by Sir John Grant, one of the leading portrait painters of the Victorian period. James records that he was paid £210 for the plate, from which up to 2000 prints might have been made. Such reproductions found a ready market in Victorian society in the era before photographic portraiture became established.