Pipers in the London Irish Rifles (a British Territorial Army unit, i.e. similar to the National Guard in the US) wear solid coloured kilts in something called 'Hodden Grey'.
Actually, that's the London Scottish that wear Hodden Grey, along with their affiliated regiment, the Toronto Scottish. The pipes and drums of the London Irish Rifles (both units are now part of the London Regiment) wear saffron kilts.

You'll see a picture of a LIR piper on the front cover of a book on the regimental association's web site:

http://www.londonirishrifles.com/books.cfm

Regards,

Todd