Hi Stuart
again me...
we used to use Bellbrush when I wa sstill in London and cleaning London buses...
http://www.bellbrush.com in Enfield/Alma Road.
They were quite good/flexible but you had to keep an eye on them too...as I assume it goes for all.
Ask for Paul (Winford I think) the Director if he is not somewhere overseas...
I can also give you another guy's tel number at Junction 29 of the M25 if you want. (Maintenance Supply) but best to speak to their sales man Andy Packham.
Hope it helps
Nico