Arbroath has a number of spots suitable for parkour practice but Morrisons is one of my favourites. I will often be here after they have closed (small town mentality).
There are a number of different sized railings suitable for bipedal or quadrupedal balance which run the whole length of the perimeter of the store. The disabled access to the store is a large permanent fixture since the store is below street level. It lends itself well to practice for fast descent and has opportunity for surprising creativity. In addition, there are various areas to practice standing and running jumps, foot placement etc.
This is located 2 mins from both the train and bus stations in Arbroath, and conveniently, 2 mins also from my house!