I did a Battlefields tour with school years ago, which finished with a visit to the Menin Gate, where they play the Last Post every night, with at least two buglers, sometimes as many as Five.
It's quite an emotional moment... surrounded by names on the walls of people who lost their lives in war hearing the Last Post played with so much pride... especially after a whole week of visiting memorials and trenches, and most of all the Ossuary, with over 16,000 graves in front of it... and the windows through which you can see the remains of some of the dead. (The sight of the crosses is breath-taking. The picture here gives you some idea, but you really need to visit this place.)
I would imagine that there's many events in those areas, I would think the greatest concentration of Last Posts would be in that area, and I would think there isn't that many buglers... could be that a couple of them do a lot of performances in a short space of time.