London Heathrow advice

We just did that transfer three days ago. It took us 55 minutes gate to gate, using the bus. I did not see a train option. Also, we were first off our flight, not last, so factor time in for that. We got off the flight, walked down various hallways for 15 minutes at a fast clip. Got to a bus area for terminal tranfers, waited a few minutes for a bus. Bus ride was ten minutes. Got to terminal five ( we were going from three to five) and had a quick passport check. Then there were staffed tables warning us about travel liquid restrctions. Then went up an escalator and came to a full security checkpoint...scanners, bag search and everything. Line to get through this was about 15 minutes. Hope this helps.

Forget the train as there is work going on disrupting service between terminals (ah, I forget which ones) and the train is outside the secure area. There is (or was a year ago) a bus service between terminals which is pretty good and they keep you within the "secure" area even if you do in fact leave say terminal 5 for terminal 3. (Not to be confused with the bus service curb side.) That said, I believe, you will have to go through passport control (not customs - that happens in Lisbon) and get to your gate in Terminal 3. (I don't believe you have to go though security again unless you are on a U.S. bound flight.) Also, it'll take you a good half hour to deplane. So yes, this is a tight connection because you will be late arriving to your gate this being Heathrow. Despair not however, it can be done and if you miss your connection, well, there's always another flight. Take calming breaths and remember it'll all work out.

Thanks Valerie & Marie for the speedy replies! Sounds like it will be very tight indeed, but hopefully doable. After the connection to get us to Lisbon we then have another connection to our final destination of Madeira, so that is a concern. Guess we will have to pretend we are on the Amazing Race! We'll be rather groggy after a 10 hour night flight.
Are the signs clearly visible for the transfer bus from one terminal to the next?

Carol If you are flying direct from West Coast, we often find our flights arrive early (not always though). Be sure to stay within the "in-transit area" and use that bus. There was good signage when we last did it. One clue is that you dont want to go through "immigration" at Heathrow

Here is the official advice on flight connections at Heathrow (from their website). Basic advice is to follow the "Flight Connections" signs! And flights to mainland Europe from the UK are considered international flights. http://www.heathrowairport.com/portal/page/Heathrow%5EGeneral%5EAirport+information%5EFlight+Connections/

Take a look at the website above as it is helpful. The " Flight Connections" signs are purple. Keep following those purple signs until you see the option to transfer to T3. This will take you to a dedicated bus that takes you to T3, about 10 minutes ride on the bus. I timed it when we flew last month, and from the time we we off the plane to the waiting area in T3 was only 35 minutes. Check the board there to find you gate. You do NOT want to use the train to transfer between terminals for a flight connection. The train is the Heathrow Express and it does provide free service between the terminals. But you have to go through immigration/passport control to get to it. The lines can be very long. We were in line there for an hour.