The aptly named “Moor or Less” report, of which Ms. Jones was an author last year, found that the number of moorings and other houseboat facilities in London was being outstripped by the rising demand.

There are not enough permanent mooring sites available for rent from the Canal and River Trust or from private operators. That means most boaters in London must now rely on “continuous cruising” licenses, which allow staying at the same spot for no longer than two weeks, before shoving off in search of the next available tie-up spot.

Some boaters, of course, do not mind living as floating nomads in the heart of one of world’s busiest cities. Even before permanent moorings became so scarce, Kevin Kibbey had by choice been a continuous cruiser on England’s canals in the six years since he retired as an officer on the London Metropolitan Police force. For the last two years, he has been plying the canals of London, where by day he works as a software analyst.

“It means the freedom to change your scenery with the turn of an engine,” he said while applying a fresh coat of dark green paint on his boat, the Rymardas, while temporarily tethered in Little Venice. “Last week, I was at Kings Cross. Next week I am going to Notting Hill.”

London’s waterways have not always been residential. Built more than 200 years ago, they are part of the 2,000 miles of a British canal network stretching from the river Thames in London to Manchester and Liverpool in the north of England. During the industrial revolution, London’s canal system was a crucial commercial transport system, conveying some five million tons of freight a year.

By the middle of the 20th century, though, canal trade was eclipsed by land-based transportation. The waterways became attractive for leisure cruisers and, eventually, residential boaters.

Although the boats are still cheaper than most other housing options in London — where the average rent on a one-bedroom apartment is now more than 1,200 pounds a month, or around $2,000 — the initial houseboat investment is not inconsequential. A new vessel can cost more than £100,000, although a secondhand one can be had for about £20,000, depending on age and quality. (By regulation, a London houseboat can be no more than seven feet wide and 72 feet long.)