Chiffchaffs

On Monday, while we were in the Reading University grounds, Zoe and I heard our first chiffchaff of the spring.  On Wednesday morning I heard another at Farnborough North on my way to work.  This morning I heard it again, and a little later, in the woods, I saw a bird that looked like a chiffchaff but which was singing a melodious song that wasn't the repetitive two-note 'chiff-'chaff-chiff-chaff'.