I've edited the link in my post above to give a more accurate position for where it is according to these photographs. The walkway behind the aircraft is a public footpath along the dock edge.
I would think it was unlikely the aircraft could be taken through the swingbridge towards LCY as I don't think the wingspan would fit the distance between the dock walls at that point. But if you look at the lower picture it can have a good run down the water from either direction, pass well beneath the high-level footbridge, and lift off after passing underneath.