Post Box fire

Walked into Farnborough town today as I needed to take my phone back for repair, only to see a Fire engine hare pass, but I thought nothing of it. Turns out someone had set a post box alight, rather a serious offence as the post is classed as the 'Queens' Mail. This made me think as there have been a number of letter bombs this week, was this one then went off too soon? On the way back up the high street the police had sealed the whole top of the street off so seems they where thinking the same as me.