Sorry both, but I disagree.
Numbers increase because more people arrive, not because those already here stay longer. If nobody else arrived it would not matter if those already here lived forevermore, the population would not increase.
Leaving aside the contentious issue of immigration for a moment, to accommodate longer life expectancy and to keep the population stable birth rates must decline. It is not possible to control life expectancy (unless you want to kill people or not offer them available medical treatment).
You are quite right, f-f, "if births continue at the same rate" then the population will rise as longevity increases. But to keep the population stable (which I believe is highly desireable if not essential) then birth rates (and immigration, to harp back to it for a moment) must fall. Mr Boles, in his wisdom, put forward the contention "The majority of that growth [in population], about two thirds, has been as a result of ageing."
The man is a bufoon.