Here is a new old stock Lucas type L661 reversing light lens for the French market as used on many classic British cars in the 1950s and 1960s, including Aston Martin, Triumph TR4 and TR4A, Sunbeam Alpine and other Rootes vehicles, Rover P6. It is different for the French market because, unlike the type used elsewhere, it is amber/yellow rather than clear.

If you have any questions please ask.