Supplier of Sushi to Nobu etc. is Atari-Ya Foods and they have a couple of shops dotted about.

Check out their website:
http://www.atariya.co.uk/jp/shops/shop_list/shop_list.html

Also the Honda factory in Swindon apparently brings over the best chefs. While you can't eat at the staff restaurant, they run a hotel which caters to the public called Stanton House.

http://www.stantonhouse.co.uk/restaurant.htm