Interesting to try and define the diagnostic features of a "cold
westerly" as opposed to the (sadly too common in past 20 years) humid
rPm airmasses with temps barely below that of Tm.

Round here (Southampton) I would say the following:

- A ground frost on all mornings with no frontal activity overnight.
Happened this morning and, most notably, Saturday.
- Clear skies overland with shower activity visible out to see.
Generally stays relatively free of showers here due to on-shore wind,
though the occasional one seems to get through (Bristol Channel/
Cheshire Gap?) rPm, by contrast, tends to be a lot more overcast
generally due to the onshore wind. In the summer the reverse is true:
"cold westerlies" often give quite thundery days, whereas rPm days are
frequently fairly sunny and warm.
- Fresh feel to air.

All evident at the moment.

Nick