Can I enter the UK as a citizen without a passport?

I'm starting to think I've made a mistake!  I just did my citizenship ceremony on Wednesday,  and without thinking I       booked a channel crossing for a day trip tomorrow.  All of a sudden it dawned on me that I may not be able to re-enter the UK using my American passport and BRP like I used to and they will expect me to have a UK passport.  Of course, I don't have one.  The UK website ( https://www.gov.uk/uk-border-control/before-you-leave-for-the-uk ) is pretty clear:
You’re a British citizen
You can enter the UK with one of the following identity documents:

a passport
a Gibraltar identity card 
I frequently tell people on here that they absolutely can't enter the US on another passport but simply didn't think the UK could have the same law.
 
Any advice?  Experience?  If I can't go it's not the end of the world but I'd rather not waste a crossing.

Take your naturalisation certificate and you’ll be fine.

They may put you in the holding pen while they validate it and tell you off, but you’ll be fine.  ESPECIALLY as you’ve JUST had your ceremony. 

Just tell them the truth, your ceremony was delayed due to covid and you are applying for your passport upon return. 

CONGRATULATIONS!!!!

Thanks for your reply KFDancer.  Since posting that, it just dawned on us that we have booked a trip to Italy in 3 weeks.  Nobody told us we wouldn't be able to travel for 6 weeks after taking the ceremony!  What an absolute PITA.  I hope our travel insurance will pay us back for that, although it's doubtful. 

You can travel!  You’ll likely get told off but no need to cancel.

That’s what the border guard said this morning, he seemed strangely fine with everything once he heard we got citizenship.  I’m in France now, coming back tonight and we’ll ask about Italy.  It may be OK.


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That’s what the border guard said this morning, he seemed strangely fine with everything once he heard we got citizenship.  I’m in France now, coming back tonight and we’ll ask about Italy.  It may be OK.


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You will be fine!  Go to Italy!

Ensure to bring back some tiramisu as a bargaining chip

KFDancer, you were mostly right! 

We explained the deal to the UK border guards on the way out and the way back in and they didn't care at all.  No holding pen, no telling off, they were super nice.  They explicitly told us to not apply for a passport until after Italy, travel on our other passports and not worry about it.  According to them, everything was on the computer and anyone could see that we are UKC and UKC can always come in unless you've just come back a summer with ISIS.
   
As far as I can tell, this is completely opposite to the government advice  and advice from law firms on the web, but I'm not going to argue.  For a while there, it looked like we weren't going to get to go to Italy and were going to have to let my daughter and her friend go by themselves and stay in the giant, expensive AirBnB. 

France was lovely by the way.  Moules frites, a proper waffle, a nice walk along the beach and home by 9.

Congratulations jimbocz!!

Sounds like your travel worries are evaporating, enjoy your upcoming Italy trip.  I assume you'll have to send in your US passport when applying for a UK passport (we had to) so that is good advice from the border guards to hold off your application until after Italy.