No Activity or Krausen

Something that has never happened to me. Brewed early Sunday and hit 80+% efficiency. I used Wyeast London Ale that was fully bloated when pitched. Over 36 hours later zero activity. No krausen, No air lock movement...nada.

It is a heavier beer (1.080) and I did not have time for a starter so it is possible that the yeast is working but not enough to show anything visable. I am going to check the gravity when I get home, but in case nothing changed what is the best course of action?

Should I buy another Wyeast pack? Dry yeast? etc?