For what its worth, Kirkwall METAR this morning....
2011/05/24 08:50 EGPA 240850Z 26024KT 3000 VCSH VA FEW008 SCT018 09/06 Q1002 RESHRA
As for the validity / accuracy of the Met Office model, IIRC, other VAAC were requesting access to it after Eyjafjallajökull as it was significantly more accurate than anything they had. However the fact is that forecasting is an inexact science, forecasts will change, and they're based on the best data available at the time of issue, which may not necessarily reflect the actual observations at the time of validity. In other words, forecast does not equal observation. Thats true the world over. In the case of ash, I would imagine it has to show worst case possible spread and concentration - in some places there will be less, in others more.
I'm much more optimistic now than I was yesterday (having not looked too closely at the charts.)
Icelandic Met Office:
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