But the white cross and black background design is also the coat of arms of the Saint-Perran (or Saint-Pezran) family from Cornouaille in Brittany, recorded from the 15th century.

The window depicts St Michael at the top and nine Cornish saints, Piran, Petroc, Pinnock,[4] Germanus, Julian, Cyriacus, Constantine, Nonna and Geraint in tiers below.

The head of St Piran appears to be a portrait of Trevithick himself, and the figure carries the banner of Cornwall.

[2] The arms of the Saint-Peran family in Brittany, show a white cross pattée on a black field.

The flag can be seen in Doc Martin, which is set in the fictional Cornwall fishing village of Portwenn and filmed in the real-life one of Port Isaac.