10 year immigration status

[umair2017]

Hi all,
I am applying for ilr next year based on 10 year route, but I may not have one or two entry previous biometric reference numbers as homeoffice takes back the previous biometric permit cards.
Is it necessary to provide those ref numbers in ilr visa application form?
can someone please let me know of this, how can we request this information from homeoffice?

[Archer1]

Hi there,
No its optional you can see in the form its written "if known"
.no worries if you don't have them leave that blank please.