I have a photographic book entitled "Portobello Road -The Early Sixties", published by the Antique Collectors' Club. The photographs recall a time when the market was more local and less international (and you could, occasionally, pick up bargains). One of the photos has this great, handwritten sign: "Very useful hard-wearing single size SHEETS" (and then in smaller size) "with slight repairs". The price was "5/- each or 2 for 9/-".
Portobello Road was originally Green's Lane and, later, there was a farm there called Portobello Farm, which took its name from a victory in the "War of Jenkin's Ear" between the British and the Spanish in the mid 18th century. Puerto Bello, as it was called back then, is in Panama.