We will be travelling through Heathrow on our way to Paris and have to transfer from Terminal 3 to 1. Thanks to all the good info found on this site I now know what to do to transfer. What I do not know is will it cost me and, if so, do I have to have pounds sterling handy? Also, can anyone tell me approximately how long it takes to get from one terminal to the other. Thanks in advance for any help you can provide.

I am almost certain you can walk between terminals 1, 2, and 3. I can't remember how long it takes, but it's not that long.

It is transferring between terminal 4 and either terminal 1, 2, or 3 that requires either a tube ride or a shuttle bus ride.

And if you do need to use the shuttle, it doesn't cost anything.

It depends whether your bags are checked through.

If they are, you follow the signs for transfers when you arrive at T3 and get the bus to the Flight Connection Centre (which is inthe same building as T1 and 2). You go through security, and continue your walk to your T1 gate. Allow 30 mins, but security queues can slow this.

If they've not been checked through, you go through Immigration, collect your bags and the easiest thing is then to put them on a trolley, walk through the underground passageway to T1 and check in. The whole walk from plane to T1 gate is 15 mins. How long you wait at Immigration, baggage claim and at the T1 security queue depends on lots of things, but can be up to an hour.

When I last did it (admittedly with a British passport, but with a 5 min client meeting on the way), it was 30 mins from T3 disembarkation to sitting in a T1 FF lounge.

Thank you all for such a quick response. I think I have all the information I need now. This site is great!