Well, I think you'll be fine, since your OG was pretty close to the recommended one, and I actually think a less attenuative yeast is actually better for a pale mild. That said, I hope you oxygenated the CRAP out of it, because that yeast can throw plenty of diacetyl if even mildly annoyed, and BOY does this strain need oxygen. In future, consider getting an oxygen stone and pure O2 if you want to keep working with British Ale strains. That's secondary, of course, if you're not closely controlling the beer's temperature and pitching the correct number of healthy cells (starters, calculated with viability using mrmalty.com and the like).
If your yeast vial was fresh, you're probably at least close to the right pitching rate, but I think you're going to want to keep a VERY close eye on this beer as far as the temperature goes (IN THE BEER, not the ambient temp) and make sure it's ideal the whole time, and then if you still get some diacetyl, warm it up for a week or two and keep rousing that yeast.
I can't be arsed to keep up this list of what's in the fermenters, but hey, check out the cool brewery I'm opening up!
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