Lost Passport Entered the UK

Hi everyone, I am applying for first UK passport and it says:

If you have naturalised or registered as a British citizen –
your certificate of naturalisation or registration and the
passport that you used to come into the UK and any foreign
passport you hold or are included on. A ‘full’ birth/adoption
certificate that shows parents details for applicants under
16 or a court order granting parental responsibility (if any
are in place). Applicants 16 and over don’t normally need to
give us their birth/adoption certificate.

I have a current foreign passport and my BRP but I lost the passport I've entered the UK with years after it was canceled. For safekeeping and also during the naturalisation process I got every pages of the passport colour photocopied. Would only sending the colour copies be enough? I don't have a lost report for my old passport because I lost it after having received my current one.

Thank you for your help.

Your current foreign passport should be fine, assuming it's the one you used to enter the UK the last time you were outside.

If in doubt, or if they should request more details, the colour copies of the pages of your lost passport should be fine. In that case make sure you include a short cover letter explaining why you can't produce the original.