I'm not doubting your experience but those photo's just look wrong for that part of Duke street. Copper stood in a little raised thing and the chain testing works was on the left after the copper just before you got to Cleveland street just after that little shop which is still there today.
I remember being held up by trains going across where the copper was. A long time ago and all viewed from a bus with my mother so maybe memory is playing tricks?
The policeman got a raised platform with a cover later on
but looking at the last photo, the chain test is the big
long building behind the policeman on the right hand side
of the road looking towards Wallasey.