There is a comprehensive list of the lamps on a website created by Alan Cordwell. As a "newbie" I can't give a direct link, but if you Google "Alan Cordwell sewer gas lamps" you'll get there! Also, you can see a map showing the locations if you Google "three legged cat sewer gas lamps" (trust me!) and select the "blogspot" entry. And, yes, it was me that drove round finding and photographing all 22 lamps, 19 of which are Grade II listed buildings. If anyone knows of any more of these lamps (definite sightings please) we'd love to hear.