I thought Castrol was a British company?
Well, I just looked on my jug of CSC and it says Castrol North America, New Jersey something or other. Maybe there's a Castrol U.K., I don't know.
Anyhow, here's a list of the ingredients:
2-Butoxyyethanol(111-76-2), Sodium metasilicate(6834-92-0),Sodium hydroxide(1310-73-2)
It's a degreaser/cleaner so check in that department. I hope this helps a bit. -Cheers
P.S. Here's their U.S. Toll Free "retail purchase locations" #, 1-800-642-0174. I imagine it would cost to call from England, I have no idea whatsoever about that.