Originally Posted by Christopher

This is correct. When a person with ILE enters the UK, assuming that the immigration officer acquiesces (as is usual), the person would be said to have ILR. An ILE visa/permit will have a date attached to it; this is the date by which the holder must enter the UK (not the date when the leave to remain expires, as is sometimes mistakenly supposed by over-zealous airline check-in staff, and others).

When evidence of ILR is transferred to a new passport, other phrases are sometimes used, such as there being "currently no time limit on the holder's stay in the UK" – which, one would have to say, is rather clearer. (The word "leave" can cause particular problems with non-English speaking officials: "leave" here obviously means "permission", but to someone with a limited knowledge of English, "leave" has only one meaning, and that is the opposite of "remain" –.what does "leave to remain" mean to such people?!)