Here's a book that we'd love to have researched. My Cool Allotment: An Inspirational Guide to Stylish Allotments and Community Gardens by Lia Leendertz and Mark Diacono, is a tour of 31 different allotment gardens in the USA, the UK and Europe. What a delight--visiting, photographing and chatting with the fascinating and diverse gardeners in Paris, Devon and Brussels among other places.
It was a labour of love for the author who has been a keen allotment gardener herself. Most of the gardens that she visited are publicly-owned or rented.