also they need to see the crowds for security so keeping them long and narrow probably works better. Just a thought, I might be way off.
I did think about that, but the system around Parliament Square (the main queue wasn't running through here) just ended up funnelling everyone in a non-moving mass because it was a long detour to get back up to Trafalgar Square.
It felt like they were creating a queue when there wouldn't have been one had people been able to disperse through the roads.
We gave up on Buckingham Palace after an hour of queuing in St James Park as the security guard said it was a 3 hour queue from where we were. There was also some efforts to queue jump over the small fence which they were doing a great job of stopping.