This cache is at the canal crossing by Cooper Mill. The outflow from where the mill stood causes some fast water for canoeists and for as long as I can remember the gates have hung over this section for their use. Summer months it can be entertaining to catch them navigate the gates to varying degrees of success.
The mill is long gone and whilst it stood as a derelict industrial site for many years, it has now be regenerated to be housing and office complex. Image below is the canoe gates and taken when only the first building has been converted.
History of the site is documented on the interwebs for anyone interested but was too much detail to put in this description.
You are looking for a magnetic nano cache. Log only. Please bring your own pen and replace carefully.