Kevin T of NB Tranquility got it. It is the breather for the ground paddles on a lock on the Huddersfield Narrow Canal. The pepperpot-shaped device seems to serve as a bollard or strapping post too.
This is at Lock 12W.
Summer Cruise Day 39 Disley to Higher Poynton - We woke to the sun streaming in through the port holes and for once Smudge was still out for the count. It took him a while to come too. Must have been a...
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