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Thanks for the suggestion, Ichkeria. I googled Venus, and found this
"Even casual skywatchers cannot fail to notice brightest planet Venus currently hanging like a lantern above the southwest horizon at nautical dusk, which is presently about 6pm GMT for the centre of the British Isles."
This certainly sounds like the one I am seeing. Very bright, hanging low in the sky to the south, and slightly west, shows up at dusk, then disappears.
A very beautiful sight. Thanks for the information.