Originally Posted by
Earthman
It's doable,I've made it to T1 via the hex.
But it's not advisable due to as said the possibility of being even 10 or 15 mins late on flight one,queues etc.
Two points a) you must be on a single ticket so that BA know about your onward travel and b) stay in the Flight Connections arena as if you go landside (not relevant to OP) and get scr*wed up by HEX, BA will wash their hands "not our problem".