Interesting stuff. In the last few years I have been researching for the National Trust at Rainham Hall and I found plans for a canal that would have started from the basin at Rainham Wharf and – if I remember correctly – continued along pretty much the same route as the one mentioned on this website, finishing in the area of the Romford Brewery. The plans were in the Essex Record Office at Chelmsford and are easily found through their online record search, although you have to go there to see them. I believe the plans date from 1809. You may be already aware of these plans!!