Family visit sponsor - no UK passport

I am due to apply for my mother's family visit visa to UK. They ask for a proof of my (sponsor) immigration status. My passport application is caught up in the Home Office backlog. We need her to come as soon as possible. My naturalisation certificate has been sent for passport application and unfortunately I do not have a copy. Can someone suggest what would be the best thing to do? Thanks

Either a) Pay to upgrade you passport application or if you can't afford that then b) try to use a combination of the reference number that was on your naturalisation ceremony appointment and that letter along with a covering note explaining where your passport and naturalisation certificate are.

But personally - I'd go with A - it's easier and more likely to be ok.

P.s. as a side note - this is always why you should take copies of anything official you send off to any organisation. What happens if the passport office lose your certificate?

Thanks mate.
I have already applied for passport, can I still upgrade to fast track it?
I thought of requesting a copy of naturalisation certificate but that costs £95!!
I thought of sending the covering letter that came with naturalisation certificate that says that your citizenship has been accepted etc etc.
On another note, I had scanned copies of naturalisation certificates. Unfortunately, the PC I had it on crashed and unable to recover any data from HDD.
Thanks for your help again

See here on the upgrade: https://www.gov.uk/get-a-passport-urgently

But even that's going to cost you another 30-40 quid.

As for the additional 95 for a naturalisation certificate ... you have to weigh it up against a possible rejection for your mum and a new application which would be another 85 for her.

Edit: Is this your first adult passport? Have you had the interview yet?

You cannot upgrade a First Adult Passport application. The upgrade is only available for renewals.

Unfortunately the OP will have to wait.

Thanks guys.
Yes it is my first adult passport. I am waiting for the interview.
I may have to go down the route of obtaining another naturalisation certificate
Or ask my cousin to sponsor her.

A replacement certificate will also take a while, it is not instant and am not sure if a replacement one will invalidate your other one you have sent with your application.

Can you not sponsor her with your ILR BRP and explain your situation regarding your passport? Can your spouse (if you have one) not sponsor her?

Or she could apply for a General Visitor Visa.

Thank you.
So if she applies as a General visitor, she doesnt need sponsor?
Is this the new equivalent of Tourist visa?
She has been to UK 6 times so far. This should give her some credibility.