Hi - thanks for that PL
The Wey & Arun Canal (which Mr. Dashwood calls the Surrey & Sussex Canal) is still not open to through navigation, but since 1970 is gradually being restored by the Wey & Arun Canal Trust, and they run popular boat trips on parts that are in water. When I lived in Sussex I used to volunteer on the working parties, clearing away undergrowth etc. It was why I was interested in recording this book, which is believed to have been the last attempt by anyone to navigate the whole route before the canal was finally closed. The Trust's website is here:
https://weyarun.org.uk
The other old canal he mentions, the Portsmouth & Arundel Canal, leading to Chichester harbour, is unfortunately derelict, and there are only a few remains of it in places. It would have been really interesting had they been able to use the canal to continue their journey. I don't know of any plans to try and restore any parts of it.