Originally Posted by
WHBM
[...]
There's only one significant way in from the terminal to the T4 station, there are ticket gates (and baggage restrictors) across the entrance, so get friend to wait there. There's also an Underground official at the gates if either of you feel like chatting. Because the trains wait at T4 for several minutes you can get off, say Hi to friend, have them come through the gates, and get back on the same train. If you don't go out through the gates and in again you won't have to pay an extra fare.
That's a plan -
this is a photo of what the T4 Tube station ticket hall looks like from the ticketed/platform side of the ticket gates, and
this is the same ticket hall from the other side of the gates (one can see the ticket machines and ticket windows).