The British Library just released over 1 million old illustrations into the public domain via Flickr, and scanned by Microsoft. The pictures date from the 17th to 19th century and include "maps, geological diagrams, beautiful illustrations, comical satire, illuminated and decorative letters, colourful illustrations, landscapes, wall-paintings and so much more". Many are pertinent to London.
The data dump is just a starting point. The library hopes that browsers will use the collection in creative ways, and it will release a crowdsourcing application next year so users can help improve descriptions of the illustrations.
For now, we can only search for keywords in the book titles, not figure legends. And, because it's on new-look Flickr, the search box is about as easy to handle as a wasp-drawn chariot. Still, if you do find stuff of interest, you can download any image you like, and put it to any creative purpose without fear of copyright infringement.
We took a look at the figures from two London-themed books, "A Comprehensive Scheme for Street Improvements in London, accompanied by maps and sketches" (Arthur Cawston, 1893), and "A History of London ... With maps and illustrations" (William John Loftie, 1884). Without having the physical copies to hand, we're not entirely sure of the context behind the images, but we've had a go at interpretation in the figure captions below. Links to larger scans can be found beneath the image gallery.