And here is the Official Plan deposited by the GJCC as per the 1793 Act.
It can be seen from this that the original idea was to utilise the two southern branches of the Brent, joining them with a straight cut around the middle of “Old England”. Due I suspect to machinations from Dr Johnson, who would have seen little profit from this route, the new line is drawn roughly along the present day line of the canalised section.
I shouldn’t have said it didn’t reach the Thames on the drawing, rather that it doesn’t show much of the original Soaphouse Creek portion. It would have been nice if they had included a bit more, but of course it was concerned only with the proposed line of the new navigation.