Wigan Album

The building looks as if it was already a few years old when the photograph was taken - it was opened in 1904.
The party are stood on a special constructed platform, which might also have served as an array of seats for the party to use whilst awaiting a special event - such as a Royal Visit. One such took place in 1913 (George V and Queen Mary), and one in 1932 (the would-be Edward VIII, Prince of Wales). By the dress, I'd say 1913 - the sergeant-major leaning on his swizzle stick on the far right looks WW1-era to me.

Rev. I'm sure most of your post is correct but I think the soldier is leaning on a "swagger" stick. Swizzle sticks are for cocktai!s.