Sure, you could. I'd probably use a more flavorful yeast for an ESB, but if you don't mind a "clean" yeast taste in it, the 1056 would be fine.
That said, you don't have to dump it even if you don't use it. Put it in the fridge, and use it when you brew an American style beer. I have many yeast strains in the fridge in mason jars.
Broken Leg Brewery
Giving beer a leg to stand on since 2006