I will be flying from the U.S. into Heathrow on UAL and connecting to a possibly tight connection on a BA flight to Lisbon. I have flown into LHR many times as a final destination, but never connected there.

1. How much time do I need to allow?
2. What are the procedures - Do I have to collect and recheck my bag? Must I go through the long customs lines?
3. Any problems or extra issues because I have separate BA and UAL tickets?

Thanks to you real road warriors for the valuable advice you provide via the forum.

Colo1K