Must be that Heathrow is expecting more global warming this winter.
29 Sep 2011 – Heathrow operator BAA today announced that it is investing £32.4 million (US$49 million) to deal with bad weather this winter, including tripling the number of vehicles available for snow clearance.
Heavy snow the Saturday before last Christmas led to near-closure of the airport and thousands of passengers had to camp out.
Heathrow has also increased staff available for snow clearance from 117 to 468 per shift and introduced a new “reservist” role, with up to 950 non-operational staff deployed to terminals to help passengers.
Thanks to Caroline Snyder for this link