2020 advent Day 14

While looking for late-autumn migrants at the coast, I came across this extremely late Garden Warbler sunning itself on 3 November!  Garden Warbler was my immediate reaction and the identification would normally be straightforward but, it being so late in the year, when any self-respecting Garden Warbler should be south of the Sahara, a comment by another birder got me wondering if it might be something else instead.

Garden Warbler, Heist (West Flanders province), November