A mudlark is someone who scavenges in river mud for items of value, a term used especially to describe those who scavenged this way in London during the late 18th and 19th centuries.
Back to Deptford Creek again.
v1 is looking up the creek under the bridge of the Docklands Light Railway
v2 - part of the creek wall
v3 - all the detritus that remains in the creek. They tried to clean up a stretch of the creek and removed hundreds of
shopping trolleys amongst all the other junk but found that the actually wildlife decreased. The little critters at
the bottom of the food chain were able to hide from their predators in all this rubbish. Hence they left all the
rest of the rubbish alone.