Originally Posted by
BA6501
Correct, they won't check through. If you don't check bags, you'll need about 30 minutes to get from the inbound aircraft to the departure gate.
That's slightly optimistic in my experience as someone who walks steadily but not briskly. Depends on the length of the immigration line (took me 15 minutes relatively early on a Saturday in May, line was not as long as some other times) and how far your gate is in T4 (could be a 15 minute walk). Train is usually quick, but not instantaneous.
Perhaps not being an EU passport holder caused me to be slower.