In reply to Greenbanks:
Average rainfall will tell you very little on it's own. Did it just rain when it was warm, or did most of the precipitation fall as snow high up? Obviously precipitation is essential at some stage for there to be ice - but the timing and intensity is probably more important than monthly or seasonal averages. In short, the total amount of moisture UK mountains get is not the limiting factor in ice formation! Temperature is obviously much more important. But again, averages may conceal important details.
A winter of high average rainfall could mean mostly wading around in powder, or climbing wet rock... or possibly good conditions!
If you wanted to investigate this it is easy to find historical weather data (see link below) - but to test the correlation it might be difficult to reliably determine when 'good conditions' occurred...
http://www.metoffice.gov.uk/climate/uk/stationdata/