We went to the Williamson Art Gallery in Birkenhead the other day. On either side of the front door was a donation box. Both had previously been post boxes.
This post box came from Wallasey Town Hall.
And this one from Birkenhead Town Hall. The Post Office notice on it points out that while the Post Office collected from the box it took no responsibility for anything lost in transit.
Outside the Gallery is one of the few remaining Victorian fluted pillar boxes with a vertical aperture from the 1850s.
Prior to 1859 there was no standard colour, although there is evidence that the lettering and Royal Cypher were sometimes picked out in gold. In 1859, a bronze green colour became standard until 1874. Initially it was thought that the green colour would be unobtrusive. Too unobtrusive, as it turned out — people kept walking into them. Red became the standard colour in 1874, although ten more years elapsed before every box in the UK had been repainted.
Judging by this early twentieth century postcard that I got from E-bay, people still bumped into them after they'd been painted red.