Playing around with different yeast strains will be interesting. London doesn't utilise maltotriose, where Nottingham seems to be better at it. As BrewnWKopperKat said, you have to talk about mash temp when you talk about yeast. This is from the London ESB technical data sheet:
"LalBrew London™...
I made a best bitter a few months ago and used Lallemand London ESB yeast. FG was 1.016 and the beer turned out way too sweet and cloying. AlexKay, maybe you can take another reading?
I recently tried the exact same recipe but using Fermentis S-04 and FG was 1.010 and tasted much better, dry...