Hi spendlove
Thank you for reminding us of this resource which has been mentioned on Rootschat previously over the years.
The Guild Of One Name Studioes launched this in 2011 with the emphasis at first on the East End of London. Over the years the database has grown but is still not complete and it might be very difficult to quantify its coverage.
If you have an enquiring mind and time on your hands, you can also use some of the data from freebmd if you also have access to the parish registers.
http://www.freebmd.org.uk/district-page-reverse-map-index.htmlYou can look at the year, quarter, and registration district and look at the range of page numbers for that quarter. Those at the lower end of the range will always be the Anglican marriages (and in the same parish order until new parishes were added) then the last numbers are register office or registrar attended. The numbers in between but after the Anglican range will be Jewish & Quaker.
As I say, you need that type of mind and time to play with the data.