"In Looking one day at Roque's plan of London (1742-5) I noticed how many burial grounds and churchyards were marked upon it which no longer existed. I made a table of them, and traced their destiny . .  ."
                                                                         Mrs Basil Holmes, London Burial Grounds, 1897

Over a hundred years have passed since Mrs Holmes recorded the location of nearly 500 burial grounds in the city and suburbs of London, of which 364 still existed in whole or in part.  Since then there have been two world wars, and development on a massive scale. At the beginning of the 21st century, how many still survive?