There is a firm closer than Sheffield, they are based to the west of London, their name escapes me if I said Thames Cleaning and drying it would sound daft but its something like that.
They have the similar plant as Franklins.
If you remember the Thames came up and flooded all the rich houses along there, Rolf Harris, Parky, Billy Connelly etc etc, a few years ago and previously 20 years or so ago.
Because of this the houses along there cant get there carpets and contents Insured so they have hard floors and Oriental rugs.
I havent used them but I know a collegue who had a big silk rug done there and it was brilliant, you can see it being done evidently.
If you look on the back of a Fllockati rug they are the preferred cleaning people on the label.
Sorry cant be more helpful but someone out in west London should know.