Hi Maybe the local Council has records. It may be that a contract to supply drain covers was tendered for. It would be surprising if there wasn't a Sewerage or Drainage Dept which had a record because of the obvious quantity and ongoing need involved. Another area where there may be records is in the manufacture of the drain covers. Were they steel/iron? You may be able to track down the foundry or wherever they were made. Lastly, I believe there would be someone who even collects such items. I don't know how you would find out, but a local Museum may be able to help, or even one of the bigger London Museums. You may even be able to find an example of one of the drain covers, or a picture of one somewhere, through researching the history of drainage and sewerage. It is amazing what people write books about. Hope you find what you are looking for. Sue R in Oz (formerly of Enfield, Middx)