Lantern is very dim and has a slight flicker

[Jupiter01]

Thanks @333rocky333. I know what you mean by the small terminal on the metal wall box but this box doesn't have one. Hence I terminated it into a terminal block. Does that mean that my screws are currently live and hence dangerous?
I can drill a hole in the wall plate and find a way of connecting the earth wire there if that is a must.

 

[333rocky333]

No there not Live or dangerous, but theres a slight chance in an extremely rare fault that the metal box and hence the screw heads could become Live, so normally you would attach the wire to the box somehow, theres a few options, preferably with a lug, you can use self drilling screws like Orbix screws, or drill and fit a self tapper. even drill and tap it, though the box maybe too thin for that.
If the box has 4 lugs you can lug it onto the unused fixed lug or maybe even use the existing screw fixing thats into the wall if there is one.

However you could do that and without testing, seeing as the switch end was not connected you cannot quarentee that the other end of the earth wire is connected