Yes his name is Patrick Mees. tel UK 01934 416642.
He cheats by making them from tube instead of channel section. But they look OK until the correct one comes along.
There's someone else in the UK who makes absolutely the right ones, but he just moved house, and needs to sort out his workshop, then he will start producing them again, here's his email:
wooky@wooky.plus.com
His name is Howard, and here pictures of his product:
He can make G3 and G3L with and without pannier brackets.