The S1 Aero rear lights are the same as the Trad front indicators, and the c2005 reverse and fog warning light lens.
They come in four colours...clear, orange, red and red (two reds).
Talk to Graham at Rutters.
The red lenses are quite hard to find, but orange and clear come up on E-bay from time to time. Check the lens for the L number. I can't remember the exact number but it's like L791. Search on that number. I've had red lenses from Rutters and they are not expensive. The lamp bodies I've always got from E-Bay.
2005 Corsa Red Roadster S1
2016 Saffron Yellow (Narrow) Plus 4