Today I posted a birthday card, doesn't sound like much does it but it entailed a three mile walk. It was hard going as the towpath was very muddy and my wellies kept getting stuck.
There is probably a letterbox nearer, but getting to it would entail a walk along a road with no pavements. I avoid walking Beano along the roads as he always wants to walk down the middle of the road regardless of any traffic. At least in the towpath we just have to dodge the puddles.