People emigrate for a variety of reasons. Perhaps they are looking to enjoy their retirement in a relaxed environment, in a nicer climate than back home; it could be that expats have moved in order to pursue employment prospects, whether moving to be a specialist needed in a particular country or to live in the hub of their occupation; some move for personal reasons, looking for a chance for a new life.
A high number of the British expat populations are made up of over 65s, with around 25 per cent of emigration to Australia being made by this demographic; over 65s also account for around 15 per cent of the British population in the USA and Spain.