We parked in a less familiar area and discovered this blue pillar box. Red, we all know, gold for Olympic gold medal winners, yes, but not blue. Painted in thanks to the NHS I presume it appeared within the last two years, when on Thursday nights at 8pm we applauded those who were keeping us safe and providing us with necessities. The paint has one or two chips with the traditional red showing through. 

It is quite possible that it has already featured on Blip but it was certainly new to me.
Edit: Here is Ann and Trixie's entry from two years ago.