Legal confusion.

[^woody^]

There is a planning application for the adjoining development so a 10 minute search on the council's planning website will provide a wealth of information. I usually work from a planning application to advise if the Party Wall Act is likely to apply, it's not rocket science.

As for your last paragraph, the builder doesn't appoint the surveyor it is the building owner. From the OP's description it sounds like a member of the public or at worst a small scale developer. If the OP approaches a surveyor and they already have an instruction or subsequently receive an instruction from the building owner then they would be acting illegally if they continued with both instructions. It simply isn't going to happen.

No surveyor's insurance will allow him to give any meaningful comment unless he's instructed and bound by the terms that his insurer insists is notified to clients.

So whether the surveyor wants to spend time searching for information, and then spend time interpreting that information - which will be very limited from the planning application data, is questionable. It will be generic at best, meaningless at worst.

Otherwise the OP needs to pay up for advice.

 

[^woody^]

And I think that last sentence is I’ll judged.

Wait for the home owner/ builder? If that is a stance then nothing will get done

The proximity of the new build , with a cellar means the PWA must apply

The op needs to write to the owner concerning this matter and advise them that if they do not take steps to start the process concerning the PWA you will be taking legal advice concerning a court injunction to stop the development. Obviously they need to coordinate with the other neighbour

The OP can't usurp the Act.
He has to let things unfold, let the process happen as the Act sets out and see what the builder does. If he tries to influence and force things then that could be to his detriment.