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Obtaining the Permanent Residence was based exactly on the same, to prove that she stayed in the UK for at least 5 consecutive years, without having any period outside the UK for more than 90 days.
Probably, the logic doesn't work in the Home Office, if a person gained the Indefinite leave to remain in the UK, but he/she can't, consequently, get the British passport without resubmitting again the same documents and evidence sent for the previous step.
In my opinion to request the same (again) it's just another way for discriminating Romanian citizen (a national of European Union member state)
Many thanks for your previous answer and for the reply.