recently found out that my Great Great Grandfather in the Northern Cemetery Grave 82 Compartment 66 thanks to Hull CC Bereavement Services . I have attached a plan here but appreciate this original post was a while ago
Looking at that map and scale (compared with the nearby house footprints) you have featured, I think you will find this Plan is only the Compartments, or Sections, in the Northern Cemetery.
You will need a
second Plan of the particular Compartment (some Cemeteries call this a Section) to find an unmarked grave.
Some Monumental Masons put the Section (at some Cemeteries sometimes lettering), or Compartment and also the Grave number near the base of a Headstone, so you might be able to work out an unmarked grave location, from how the surviving headstones are numbered and set out, nearby.
It it survives a Cemetery Section usually has a Marker to one corner, usually number/s or letter/s.
Mark