Through the bottleneck

Entering the picturesque bottom lock and, below, beginning the staircase

The delightfully named Grindley Brook is the Llangollen Canal's equivalent of a motorway contraflow. The perenially heavy canal traffic is suddenly funnelled into a cluster of six locks, including a three-lock staircase.
A staircase, for the uninitiated, is a chain of directly connected locks: going uphill you enter the bottom one; fill that up with water from the (already filled) middle one; go into that, fill it from the top one; go into the top one and fill that from the canal ahead. Got it? The only complexity is the need to make sure all the locks are properly full - or empty - before entering the chain. And the staircase is inherently wasteful of water - if one boat goes up, all the lower locks have to be emptied of water before one can go down.
For that reason, a lock-keeper is on hand to ensure boats go either up or down in small processions (and to make sure we don't find two boats facing each other in mid-staircase!).
As you can imagine, the whole place can become a serious bottleneck in peak holiday times - witness the ranks of bollards for the queue-ers. It's also a goldmine for the lockside @29 cafe/shop and for the little back garden craft and secondhand bookshops in nearby houses.
It's a curiosity that the rest of the world passes such a busy and historic by without a glance. Step a few paces away to the road beyond and you wouldn't know Grindley Brook was even there.
Perhaps that's for the best. Let us boaters make our mistakes in peace !