Applying for first passport after naturalization - how are docs and new passport returned?

[xyzzy]

I will soon apply for a first British passport after naturalization. I'd like my supporting documents and the new passport to be sent to me by the most secure/trackable way possible. How does this work, in particular which of the following is it?

* I send a self-addressed Royal Mail Special Delivery envelope to the passport office along with my supporting documents.
* I don't send such an envelope but the passport office sends it by a tracked/secure means themselves (possibly on additional payment).
* I can choose between the above two.
* Something else entirely.

Thanks!

[contorted_svy]

They won't use pre-addressed labels or any shipping materias you will send them. Best option is to pay for the £5 secure delivery when you apply - note that it may well happen that they will fold your naturalisation certificate.