Anyone has an idea how to change the FFN after booking. I have BA Silver (and collect TP there). Only at check-in or is there a way before for Cathay bookings?

£367 is absolutely not free 🤣
I assume if one 'wins' then they can change the FF number on the booking to BA to get the Avios and Lounge access?

Not online (at least i didn't figure it out). Hopefully at check-in.

I think the best option is at check in, or if that did not happen then at the gate (before boarding starts).
If they for some reason can not change FF number, another idea could be to ask them to remove CX FF number from the booking, and then you should be able to add BA number via BA website or app.
If you ask at the gate, it might be a good idea to also ask them to re-print the boarding pass to double-check that it shows the new FF number.

​​​​​​​You should be able to use lounge access even if you don't change FF number on the booking, just show your BA membership QR code - but this might not always be accepted, so it is still better to change FF number.

CX is being pretty sneaky here. They allocated so many "free" tickets to the UK (3,260 to the UK, compared to 2,980 for Paris+Frankfurt+Tel Aviv+Zurich+Madrid).

But they know that most winners will balk at the high taxes+fees and won't purchase the ticket. Winners can't transfer their tickets, so CX is effectively giving away a fraction of the 3,260 "free" tickets.

Makes sense why they email each winner a unique promo code for the UK giveaway, instead of dropping a promo code that's valid until all the flights are gone...

On the contrary, emailing each winner a unique promo code is the standard for the giveaway worldwide, and not a deviation from the norm. The first Mainland China round, South-east Asia rounds, and the Swiss and German rounds (held alongside the UK one) had the same quiz + wait for email format. Only the French/Spanish/Israeli rounds had the book-first via discount code format at the moment.

Just wanted to temper expectations but it is likely you won't earn a single Avios or TP on this booking. According to this (https://www.cathaypacific.com/conten...ions_EN-GB.pdf), tickets will be awarded in fare subclass O. While they did explicitly mention it will earn Asia Miles, O class on CX doesn't earn anything on any of the other oneworld carriers except AS

The moment of truth will be in 4 days time for those of us in UK!
I am not holding my breath.

​​​​​​​you can change the ff number by managing the booking as a guest

I tried this, but don't get this to work. It still shows "Green member" and I don't find a option to change it. Is there some "trick"? - Thanks!

Edit: Wrote to fast, my bad. If anyone else is searching: Quick links -> Frequent Flyer Program

Does anyone receive the promotion code already? Am I just out of luck or they haven't sent it out yet?

Haven't received anything yet.

Nope. Still waiting! I keep refreshing my inbox!

Just got the email and booked my tickets. It was £328.91 in taxes/other costs. Even high summer is still available to book.

Updates
 

Anyone received any response from Cathay?

Yep also had confirmation now (and was about 6000 in q)