My neighbour has trespassed in my garden to cut branches of another neighbours overhanging tree,what can i do?

my neighbour has cut branches down that clearly overhang my rear garden, the tree is rooted in another neighbours garden, he has clearly trespassed on our property, he has damaged an inflatable spa located directly beneath the cut branches, we have confronted him and he has admitted cutting the branches down but strangely he claims he did'nt enter our garden to do it but there is'nt any other way he could have done cut them down and he will not take responsibility for the damaged spa ! The tree also has a preservation order on it and he did'nt get any permission to hack it to pieces. What are my rights ?