I believe the issue with snow clearing is that we are not guaranteed a significant amount of snowfall / frost in a year to purchase top class ice prevention, snow clearing machinery.
What is usually purchased are machines and just enough of them to get by if there are snow fall/ice occur.
At the smaller airports this wouldn't cause so much of an issue as theres less traffic and more chance to clear / solve the problem with minimal delay. But at a larger airport all relevant systems / machinery / chemicals should be purchased in order to reduce the risk of this happening and causing the risk of aircraft diverting and loosing revenue on landing fees.
The question is now that Gatwick is up for sale, are BAA neglecting the airport and services it provides? I believe this has an overall bearing on the current issue.