Anyway, this one is at Harlow, just by the railway station if my memory serves me right. I don't have a clue why it was made this thin. I suppose it was about four inches square. I thought balance beams were supposed to counteract the weight of the gate, and the gate was normal size. I remember the gates were easy to open and close, so it works OK.
If you've seen a slimmer one, I'd be interested to know of it.