"Unsurprisingly, the full facts are a bit more complex than Scotsman."
I was actually referring to the original council report on this, produced a few years ago (2010 I think), where they were predicting that Gillespie's catchment would be full by 2015. That did explicitly propose a move to Tynecastle, and Tynecastle alone. Presumably the officers were told to think again, hence this new report, which I hadn't seen until now. It's a much more balanced appraisal it must be said, and the demographics at Tynecastle must have changed in the intervening period as it was significantly under capacity six years ago.
Anyway, yes things are more complicated than just parents gaming the system. I only mentioned it because the person selling me a bike admitted, completely unprompted by me, that renting in the catchment was the reason they didn't have room for their bikes. So it's certainly going on: this person was advised by someone else to do so...
What I have observed is that the crisis of 2008 led to a drop in the number of young families upping sticks and moving to the suburbs and dormitories once their kids were of school age. This has led to a rise in rolls at primary schools. Also, there has been a big increase in people moving to Edinburgh from all over the world, part of a global trend in increased mobility. Many of these people either have children or start a family once they arrive. Many are renting accommodation in more central districts of the city. So this has had an effect too.
I also know from speaking to parents that many do intend to move to another catchment before their child reaches P7 (or indeed have already done so), in order to secure a place in a school which is perceived to be better than the local high school. If you're renting, then it makes sense. Or even you rent somewhere else and rent out your owned flat.
We're not doing that, but are intending to enter the lottery of the out of catchment placing request system instead, as we're not impressed with the catchment school. Not bothering with Boroughmuir or Gillespie's though: little chance of success and awkward to get to for our kids, having to go through the city centre en route...