Overseas Citizenship Application - Return of Documents

I applied from The Netherlands for the registration of my son as a British Citizen under Section 3(2) BNA 1981. As an overseas application, this required me to send supporting documents by regular post, rather than having them scanned. These included the original of my son's Polish passport.
The application has been successful and we have received the registration certificate, via regular post, on 13/4/2021. But we have received no information concerning the return of the supporting documents.
How long do I have to wait? And will they be sent by regular post or courier?

No answers, unfortunately.
I'm totally stuck. I need my son's Polish passport back following his successful overseas citizenship application. It's his only ID and travel document. And I will need it for his first British passport application.
I just want to know when, and how, I will receive them here in The Netherlands.
Does anyone have any suggestions for any Home Office email addresses that I can use to chase?

Try this website:

https://www.gov.uk/contact-ukvi-inside-outside-uk

Thanks, but it doesn't help. It takes you to an online form. "Contact UK Visas and Immigration from outside the UK" where you pay to send an email. I used this form before and got the reply:

Thank you for contacting UK Visas and Immigration International Contact Centre.

With regards to your enquiry, we do not deal with British Citizenship enquiries, please contact the concerned department below:
Citizenship and Nationality Enquiries
Email address: nationalityenquiries@homeoffice.gov.uk
Telephone: 0300 790 6268
Monday to Thursday, 9am to 4:45pm
Friday, 9am to 4:30pm

So I end up going round in circles! The 0300 number is useless when calling from overseas.

I find it incredible that I cannot look up the answer to a simple question.

"When, and how, do overseas citizenship applicants get their documents back, after the successful processing of their applications?"

There is an online Return of Documents request form. But it is made clear that it should not be used in this situation.
https://eforms.homeoffice.gov.uk/outrea ... 1618318170

Totally agree it's a frustrating situation.
May I suggest another email from searching through postings: nationalitysupport@homeoffice.gsi.gov.uk
In the past it has been used with responsess being received .....

Thanks. I haven't tried that email yet.
But I just managed to speak to a real human being at Visa & Immigration, via +44 (0)203 875 4669 and he answered my question!
He says I should receive the documents 10 working days after receiving the registration certificate. I received it on 13/4/2021.
He also said the documents would be sent to me by courier.
He said that if I did not hear anything within the next few days, to chase using: furthernationalityenquiries@homeoffice.gsi.gov.uk
I feel reassured and will wait until the end of the month.

Still no documents, or any news.
I have just called again and this time received different advice. Which was to write, via regular post, to the UKVI address in Liverpool that I sent the original documents to. So I have just done this.

This was what I wrote. Hopefully I will hear from them very soon.

I am the father of XXXXXXXX (date of birth X XXX XXXX) on whose behalf I submitted an overseas British citizenship application (XXXXXXXX) on 31 Oct 2020.

This application was successful. On 13 April 2021 we received, by regular post, his registration certificate (XXXXXXXX) dated 7 April 2021.

We have, however, heard nothing about the return of XXXXXXXX’s supporting documents. Not having his Polish passport, in particular, is becoming very inconvenient for us. It is XXXXXXXX’s only ID and travel document. We also need it to apply for his first British passport.

I would be very grateful if you could return our documents to us as quickly as possible

The documents arrived back in The Netherlands, from Liverpool, today 27 May 2021.
The covering letter from the Home Office was dated 7 Apr 2021, the same date as my son's certificate of registration. But the customs declaration on the envelope was signed and dated 18 May 2021.
Very happy that my son has got his Polish passport back. It's been 7 months!
I now have to send his birth certificate and Polish passport copy (only a copy is required for overseas applications, thank goodness) back to Liverpool for his first UK passport application.

Thanks for the update - it was a long time to be without his documents.
What surprises me is that the package was checked by customs - I know it's somehow to do with brexit but we never had to worry about customs declarations when UK was still in the EU and one sent something to a third country.
Anyway, good luck with HMPO!

Thanks. I suspect the Customs Declaration, by the Home Office, for being responsible for the delay. They never had to do this before when sending documents to the EU. The weight and value of each document was specified. A nice Brexit-induced bottleneck to slow things down.