Hello, I'd be really grateful for some urgent advice. I've previously posted this in the property section, but am posting it here too for traffic.

We live in a Victorian terraced house with an external staircase at the front leading to the front door. There's also a front door on the ground floor (a bit like the Albert Square houses in EastEnders). Our steps are connected to the next door neighbour's. He is currently doing his house up and today has started hacking at the front steps to take them away. He has decided he doesn't want 2 front doors - he will replace the upper door with a window and use the basement door. We are worried that removing these steps will have a structural impact on out property. AIBU, or should a structural engineer be involved? Does he need a party wall agreement to do this?

We're really worried, so would appreciate your expertise!