pretty clear in the west, cloudy to the east, and from where i was in
west london i could see very purple sky to the north as you mentioned
but to the south-east there was an amazing band of cloud above the
horizon that was fiery yellow. above this, for a very brief period,
was a very narrow band of cloud of a green hue which i've never seen
before. i've seen references on the web to the 'green flash' but that
seems to be in clear skies at the moment of sunset - this was nothing
like that.