Hi Andy

Have to strongly disagree with your method - You would effectively be earthing the neutral which is not allowed under
6.1.6 – pg 83 – Neutral shall not be connected direct to earth on the load side of point of control.ED 1.8

It will also create a fire risk if for some reason you lose your incoming neutral from the street , The complete installation will be using the neutral/ earth , Star point as reference - The amperage could increase drastically on your pieces of 1,5sqmm wiring. Even worse if the complete street tries to earth through your star point