Ack what was it!

I heard a bird down by the river today, I know the song but I can't think what is was!  It sounded a bit like a skylark but it wasn't a skylark.  I've heard it before but can't remember the owner of the voice and I think the time of year has thrown me a bit as I'm sure it's something I normally hear in the summer not in Feburary even when the sun shines!

Does anyone know what sounds a bit like a skylark but not quite?  I'm trawling through the RSPB songs at the moment trying to find it!

Oh, and it was singing low down, not flying, in some scrub right by the river possibly on the ground possibly on one of the branches/stems.  And I'm North of Dundee, Scotland just in case location helps.

*goes back to listening to bird songs*