David Hansen wrote:
On Wed, 05 Mar 2008 23:31:55 GMT someone who may be "Clot"
wrote this:-

We do experience periods when anticyclonic weather affects large
parts of the UK at one time.

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Winter anticyclones

These, it is alleged, frequently becalm the whole country and cause
problems for the system operator, due to the absence of any wind
power, especially at periods of peak demand. The capacity credit, it
is argued, is therefore zero. However, the Environmental Change
Institute at the University of Oxford was quite clear when appearing
before a House of Lords Select Committee [12]:

"We have looked at that [stationary anticyclones in the middle of
winter over the British Isles] occurring in the wind data and the
wind data does not show it."

Several authors, including National Wind Power, have also found that
peak demand periods actually tend to coincide with above-average
wind plant output [13]. The reason for this is that wind output will
tend to be correlated to periods of high peak demand, as one of the
key factors in determining the load on the electricity system is
wind speed. Cold, windy days will lead to increased demand for
heating.

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http://www.sd-commission.org.uk/pages/230505.html Full report,
Annex B.

I'm surprised at this. I wonder how the stats were pulled together. Thanks
for the link. When I've a bit more time I'll read that.