I brewed an ESB from extract just before the weekend and then got called away this weekend and wasn't able to make any observations for the next 3 days. I checked after 12 hours and didn't see any bubbling but after coming back home 3 days later there still wasn't any bubbling happening. I did take a reading with the hydrometer that came out around 130 (~100 F). What sort of hydrometer reading would assure me that the primary fermentation occurred while I was absent?
I also ended up pitching my yeast (liquid, and I think London style/type) at probably too high of a temperature because of a crappy digital thermometer that was malfunctioning so this is why I'm concerned that fermentation may or may not have kicked in.
edit: This is just my second batch and the first one was a while ago. Also there does appear to be a ring of crud just above water level and it appears that some sediment is forming on the bottom of the container (around a centimeter). Also my hydrometer reading is 1.020 (1.035 OG roughly adjusted for temp).
Link to pictures to show crud ring and sediment: