Looking at your strike temperature and pounds of grist, I'd wager you mashed cooler than you expected, unless you actually measured the mash temp. Especially if your grain was a little cooler than the calculator assumes, you could have been below 150. How's it taste?
Edit: That is a lot of crystal malt. Even if you mashed low I'm really not seeing how your FG could get so low with all those unfermentables. How does it taste? There may be something wild in there chewing on your beer. I like my ESB dry (a la Alesmith Anvil) so I mash it low, around 150, and let the crystal and the yeast add back a bit of mouthfeel. It typically finishes around 1.014.
I can't be arsed to keep up this list of what's in the fermenters, but hey, check out the cool brewery I own!
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