There are many reasons why you may need a Party Wall Surveyor with regards to a party wall, these could include any of the following:

.Taking out chimney breasts on the Party Wall.

.Putting in a loft conversion.

.Extending your property.

.Carrying out works to a Party Wall

.Carrying out excavations within 3 to 6 metres of an adjoining property

.Building on the boundary line

.Repairs to Party Fence Walls

.Boundary Wall Disputes

If you're thinking of any of the above, then you will need to ensure any work you do adheres to The Party Wall Act etc 1996.