Actually, going back and look at your times again, between 4.30 and 5.30 would probably have been too late for the comet - sorry :(
At 4.30 it was only half a degree above the horizon (ie the width of the moon) so unless it was exceptionally clear and you had a high vantage point it's more likely to be Venus, which would have been a good span and a half left and up from the Sun and well clear of the horizon.
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simon
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