The link to a post on Canal Forum is some 11 pages but is well worth a read if like me history of the canals is your forte.
The water level is down and some of the boats are showing. If I had spent more time searching the whole area I would for sure have found more but you do not let Jaq`s lovely lunches go cold.
It seems the boats were floated in via what is now Harefield marina through a man made gap into the old Quarry. The gap was then filled in and the large number of boats have remained there since the early 1960`s. This page on the forum gives an idea of how many boats are there, SCROLL down to the aerial picture that has the overlay as I can`t get a direct link to the piece.
So maybe this is the answer to un-licenced boats, into one of the many old flooded quarries for say 1 month then sunk if no licence is obtained.
This post reminds me of the old work boats dumped half way down the Marsworth flight. Give me a shout if you want details as I can`t find the post i did at the time.