In this episode, we’re investigating an 18th-century family portrait of a young man at the prime of his life. Could a chance sighting by Philip have revealed an undiscovered work by the giant of Regency portraiture Sir Thomas Lawrence?

This painting has been passed down the generations of the Cecil family as the work of the pioneering female artist, Maria Cosway, but Philip believes it may be a case of mistaken identity. And the difference in value is enormous – as a work by Maria Cosway it is worth about £8,000; if it turns out to be by Thomas Lawrence, it could be valued at around £500,000.

The painting belongs to Hugh and Mirabel Cecil. Philip happened to catch sight of it when visiting their home and immediately complimented them on what he believed was a beautiful painting by one of his favourite artists, Thomas Lawrence. The Cecils put him right - as far as they were concerned this is a portrait of Hugh’s distant ancestor Peniston Lamb by the little-known but fascinating artist Maria Cosway. It’s now time for Philip’s hunch to be put to the test.

This investigation takes us to some of the grandest houses in the country. Peniston Lamb was part of the Melbourne family. They were right at the heart of high society, connected to royalty, and one brother, Lord Melbourne, even became prime minister. Fiona traces the provenance from family pile to family pile, charting its path down through the generations.

Along the way we learn about the pioneering artist and musician Maria Cosway. Born in Florence to English parents, Maria came to London as a teenager. She was soon noticed and taken under the wing of the influential female artist Angelica Kauffman, who encouraged Maria's artistic talents. She also had the patronage of Georgiana, Duchess of Devonshire, and the team visits Chatsworth House to see a stunning portrait of her by Cosway. Can the same hand be seen in the Cecil’s portrait of Peniston Lamb?

Meanwhile Philip needs evidence to back his case for Lawrence. He visits the V&A costume department to see if he can more accurately date the painting and find out what Lawrence was up to at this time. Lawrence was a precocious talent, painting the Queen herself at the age of 17, and he certainly moved in the same circles as Peniston’s family and painted some of his siblings. But so did Maria Cosway...

If Philip’s hunch is right, generations of attribution to Maria Cosway will turn out to be wrong and an undiscovered Lawrence will be declared – but which way will the evidence stack up? Show less