According to the Wyeast site ...
http://www.wyeastlab.com/yeast-strain/london-ale
... 75% is "bang in the middle" but ironically using the formula ...
Attenuation = 100 % * (starting gravity − current gravity) / (starting gravity − 1)
... an OG of 1054 and a FG of 1014/5 gives an attenuation of 75% which is what's desired.:thumb:Personally, I like a dry Bitter which is why I use the Gervin Ale yeast. However, according to BrewersFriend this has an attenuation of 77% ...
https://www.brewersfriend.com/yeasts/-gervin-ale-by-muntons-gv-12/
... which is at the top of the attenuation range of the Wyeast!:thumb:God I love this bobby!:headbang:Even the "experts" can't seem to agree!
That is the wrong yeast
http://www.wyeastlab.com/yeast-strain/london-ale-iii
That is the one I used, its actually the boddingtons strain apparently
Dont get me wrong I dont mind gervin yeast, I just find it a bit boring and bland I like yeast bringing something to the party. Sadly I have found all my English styles have been considerably better for the use of liquid yeast. I say sadly because well the use of dry yeast is a nice convinience but the additional hassell of Liquid has been beneficial in my expereince.