Another photo as promised for scale.
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If this bird is the same size as the Goldfinches, which it does seem to be, then it probably has a wing length in the high seventies, which would put it beyond the limit for cabaret , but okay for flammea. Gut feeling is that it is a flammea, but...
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Lat/Lng: 50.9597, 0.2758
OS grid ref: TQ599202