Thanks Ged, strange eh? I came across a picture of the church with the "bell tower" yesterday on Lancashire Online Parish site and was a bit puzzled by it - as the Herdman view shows a more modest dome. This is the same descrition you find in The Stranger to Liverpool. I have a 1820 edition and it says:

"CHRIST CHURCH. It is build of brick, ornamented with stone. It has no tower; but a light and well constructed dome, or cupola, rises from the north end..."