Recorded Delivery sticky label art

I’ve noticed a few pieces of sticker art- tags and pictures magic markered onto labels for easy application- on lampposts around Manchester. What caught my interest about a particular bunch was the labels they were on, on close inspection they turned out to be Post Office recorded delivery stickers. There are quite a few of them around Manchester, but I thought they were localised. Until today, when I found some in Birmingham. I should start taking pictures of them. Anyone else seen anything similar?