This is, apparently, an analemmatic sundial, one in which you are the gnomon. You stand on the month in question and can tell the time depending on which hour pillar your shadow crosses, with the outer circle for UCT+00:00 (Greenwich Mean Time) and the inner circle for UCT+01:00 (British Summer Time).

Though this photo was taken in Port Sunlight, there was no sunlight at all so it was impossible to verify whether the sundial actually worked.

(Photo taken in September 2018)