The London borough boundaries with fewest crossings

Some London borough boundaries are easy to cross. The boundary between Croydon and Bromley, for example, is 10 miles long and can be crossed in over 40 different places. But other London boundaries are much harder to cross, or in a few cases impossible except by boat. So let's investigate... The London borough boundaries with fewest crossings It's best to do this in two parts. a) Boundaries along…