Local Post Box Finder
The Local Postbox is an online resource for you to find your closest postboxes. It pin points the location of Royal Mail postboxes using google maps, shows the best route by car and tells you the distance along with the collection times on weekdays and Saturday.
The site is also responsive so works well on mobile devices.
The data unfortunately is not 100% correct or complete.
Dataset Provider: Royal Mail
Royal Mail Post Boxes Dataset URL: http://www.whatdotheyknow.com/request/location_of_every_post_box_that