Anyone know who provides the BBC Weather pages with their air
pollution forecasts ?

The BBC London weather page at

http://www.bbc.co.uk/weather/2643743

shows "pollution LOW"

whereas the more authoritative page at

http://www.airtext.info/

shows

Forecast of Air Pollution Index for:
Saturday February 11th, 2012
Central London:
MODERATE air pollution expected everywhere

Indeed, it looks as if the level appears to be 6 at the high end of
the moderate band.