The wall would be subject to the party wall act but belong to you. If your neighbour later decided he wanted to make use of it then he would need to pay for half the cost (calculated in the value at the time of his - not your - work).
Bear in mind that the party wall act also covers excavations near the boundary. Check out the diagrams in the explanatory guide.
Bear in mind that the party wall act also covers excavations near the boundary. Check out the diagrams in the explanatory guide.