Does anyone know where the large and long Turkish green peppers can be sourced in the UK? The ones you often see served with meals bbq'ed. Like the ones on the left here:

I've not seen them in supermarkets or greengrocers, just wondered if anyone knows of somewhere to try. Not Stoke Newington or Haringey though, somewhere perhaps national - thanks 
Well I've tried all supermarkets, M&S and a greengrocer here. Nearly all have the red ones. The greengrocer was able to show me that he knew what they were like, by using his fingers to show a rough diameter of them and then showing me roughly how long they grow. Then he told me he only does the red ones.