Hi, I used the online Heathrow connection planner at heathrow.com, and it said I would only need 90 minutes for my connecting flights (I'll have 2 hrs and 40 minutes). Is 2 hrs and 40 minutes enough time to take the shuttle between terminals and get through security for an international flight? I won't have any bags to check in (I'm taking carry on only).
Here is my itinerary:
Inverness to LHR - arriving at 8:50am (Terminal 5)
LHR to SFO - departing at 11:15am (Terminal 3)