I've seen conflicting information so I'm posting this familiar question. Heathrow is a bugger for security -- in my experience -- and they seem to change depending on who you get or when you are flying.
We are flying BA from Seattle to London to Inverness Sept 1 & 2. When we land at Heathrow, will we have to go through Passport control there? Then, we'll be in a BA lounge until our BA flight to Inverness 6 hours later. Will we be required to go through Heathrow security before boarding the flight to Inverness even though it's in the same terminal (5)??? My daughter is coming with us and she's understandably anxious about the LHR strictness about the liquids baggie. She knows I've experienced two times they have thrown away some of my liquids because either they didn't fit in their baggie (1st time) OR they didn't fit when the baggie was zipped (second time). They even threw away something my doctor's note said I needed (I'm diabetic). So they are super strict and vary their restrictions.
Please respond if you've done this sort of flight pattern within the last 3 months. I've seen answers both ways and I've also tried their website at https://www.heathrow.com/connecting-flights which doesn't help much. Thanks!