I returned later in the evening to find it again very quickly and get some poor shots of it as it was very mobile and flighty, never coming very close.
The song began as Willow Warbler (about 75% of the total song length) and finished with a 'chiff-chaff'. Very occassionally it would start with a chiff-chaff. The bird appears to be a Willow Warbler, albeit a rather dull one and into the bargain it is rung!
A Garden Warbler there was a welcome yeartick although I managed to miss a reported Turtle Dove in Semere Lane which Glen told me about.
Yearlist = 193
'Mixed-singing' Willow Warbler