I have scanned and stitched popular edition out of copyright OS maps at 300 dpi. 1950 SW London and 1951 SE London. Temporarily available here: http://www.nickhill.co.uk/map/ordnance_survey_London_SW_170_1950.jpg http://www.nickhill.co.uk/map/ordnance_survey_London_SE_171_1951.jpg Around 11Mb each.