Trees behind St Annes Crescent Pembroke

We asked Richard Staden to place TPO's on these remaining trees, the largest was felled in the last weeks. He said trees in private gardens cannot be given TPO's. We asked for the trees opposite the Bush Filling Station to be given TPO's but he said that this was unnecessary.
We have many outstanding questions about TPO's unanswered.
Trees according to him are not subject to TPO's if on private land and TPO's are unnecessary on public land. Why have a TPO Officer. What about the Devon House site the Tudor House site and Rocky Park.