Party wall dispute

[Fredbear_65]

Hi, New to here but seeking advice on a party wall issue with a very difficult neighbour. We have a storm porch and want to enclose it by adding UPVC double doors. Our neighbour claims the wall we wish to attach frame for doors to is a party wall however we feel it is our wall as it forms the internal wall of existing storm porch and is there solely to sit the supporting beam for porch roof.

[des8]

It is not what the wall does that makes a party wall,: it is its position on the boundary.

Does the wall sit astride the boundary?
Does it abut the boundary but is solely positioned on your side of the boundary?