Lost expired pasport with original ILR stamp

[MvL]

I'd like to get some advise and check if I need to take action.

I received my Indefinite Leave to Remain letter and stamp in my Dutch passport in 1993. I have long since lost this expired passport but still have the letter. I've never taken the effort to have new passports stamped to be able to proof my status, as moving in and out of the country with an EU passport is normally seamless.

I've been informed that regulations have changed and that the ILR stamp now needs to be present in current travel documents. Please could anyone let me know if this is the case and if I require the original stamped passport to proof entitlement?

Suggestions on a path forwards welcome.

[vinny]

Once Brexit is completed, you may need current valid documents in a hostile environment. It's probably in your interest to apply for NTL or naturalise before the UKVI routinely destroy their records of your ILR, if they haven't done so already.