Applicants who are granted Indefinite Leave to Enter (ILE) at a visa issuing Post should have no time restrictions on their stay in the UK, that is, they can stay indefinitely. ILE carries the same entitlement as ‘Indefinite Leave to Remain’ (ILR) which is issued by the UK Border Agency to those who have already travelled to the UK. Anyone who has ILE does not have to apply for ILR when in the UK.
Although indefinite leave, by definition, will not expire, the ECO is unable to issue a visa to those who meet the criteria for ILE without putting a ‘validity date’ on the visa. In cases of ILE the ‘validity date’ on the visa should match the expiry date on the passport. When the applicant gets a new passport, they can apply to UK Border Agency for a transfer of conditions into their new passport. They do not need to apply for Indefinite Leave to Remain (ILR).
Such leave will not expire despite having no dates of expiry, but you can apply to have the stamp put in a renewed passport.