Initially there didn't seem to be much to say about Lock 3. However, after being presented with a bit of a mystery with the photograph below, it became apparent that there was more to it than first appearances indicated. You could be forgiven for thinking that this picture looks like another shot of Bottom Lock House taken from Lock 2 but closer scrutiny reveals that several things don't quite fit. For example, the building is quite different - it has no chimney and no windows. It also appears to be in a different position in relation to the lock and the angles can't be replicated from Lock 2.
A mystery solved!
After a couple of trips to investigate, things became clearer. The scene is Lock 3, viewed from Lock 4, and there used to be a building next to the lock that is not described in any of the present local history or canal publications. It doesn't look big enough to be a cottage and was possibly some kind of industrial building - a small warehouse or storage building perhaps. If further evidence is needed before you're convinced, take a look at the footings that can still be seen directly alongside the lock.
Footings at Lock 3.