Someone has suggested that it’s a rule that all subs must warm up in the opposition half as the linesman. Which would virtually always be on the left of dug outs. If that’s the case you’ve got a pretty small area where you’re allowed to pass between the home technical area and the pitch.
I can’t find anything to verify that though. Maybe the guy who said it can give a source for that info?
I’ve been trying to recall where away team subs normally warm up. As ridiculous as it seems, despite going to probably something like 500 games at this ground, I can’t ever remember noticing before.