Richard Prior
Halfway up an Alp
It was RW to me which I am very familiar with...........it hadn't occurred to me that it might be Marsh Warbler...........very rare in Sussex, as you know I'm sure.
Too right, I never saw one in my 20 years' living in Sussex, though there was a bird that caused great discussion/ near fisticuffs on the west side at Pagham one year, a Reed Warbler with a particularly varied song was the eventual consensus reached! After 9 years living up here, the situation is reversed, a Reed Warbler would be amazing, Marsh warblers are common!!
If there's a reedbed fairly near let's hope you'll be seeing more of the species chez vous, especially once the young are on the wing.