I think the intensity and duration of this ''snow shower'' caught them out some what this morning. Three durations of single runway ops due to braking actions slipping from ''good to medium'' and then down to medium in a short space of time. Only a matter of time before the accumilations went above the ATIS 25% and turned the braking action to poor. ATC low vis ops were in force as was runway 23 as a parking area. So congestion, de-icing delays, hold over times, all these factors leading to delays and cancellations. My heartfelt thanks and congratulations go to the ATCO 121.90 (lady) this am about 1130 to 1200 who under duress from us 'busdrivers' managed to keep her cool and sort out a very trying time for us all. Thankfully HAL/BAA did manage to keep operational delays to a minimum, the main reason for the delays and canx flights it would seem would be lack of de-icing and preparation by some ground handlers for this contingency.