Oh dear
the parties probably intended this so did not write on paper
Chris' analogies are by and large unhelpful - the question should be - does permission and the right to PARK the car pass with the land or does it die with the giver ?
and the answer is - it depends and was discussed in Tulk v Moxhay 1848 - and there is a little plaque in Leicester Sq which commerates this
X ( Tulk or Moxhay or someone else) agreed not to develop and their lordships said the agreement travelled with the land and did not die with the owner
https://en.wikipedia.org/wiki/Tulk_v_Moxhay
well you dont have a written document so I am not sure if it does you know ( right travels with the land)- my fave Barmaid specialises in this.
It is not so much a question of who owns it - as who maintains it and can they have access to do it ?
( which you will notice is NOT a restrictive covenant)
Lawyers rub their hands at his sort of thing ( mega fees) and land law students scratch their heads over this
I actually would wait and see -
there is already a sign of a dispute when they say - they cant cede something which is not theirs - I think they can - "the land is A's - the wall is B's and maintenance is due solely to B and B have access to do it on reasonable notice to A."
well that is my shot anyway and yes I hve been involved in a wall dispute ......