'BLUE PLAQUES' are familiar to anyone visiting London. The scheme to commemorate addresses associated with famous people (also some infamous and not-so-famous people) dates to 1867 but back then the Blue Plaques were actually Brown Plaques. Blue turned to Brown when the London County Council took over the scheme in 1901. The LCC's successor—the Greater London Council—continued the program until 1986 when it was taken on by English Heritage where it remains today. See Wikipedia for a good summary.
For an entire listing of London Blue Plaques and for all the details as to history, design and manufacture, selection criteria, etc., go to the English Heritage website.