@clacke @cujobyte Improved health care and living conditions within a person's lifetime can substantially improve their life expectancy if they survive that long.
At day one a UK 1940s baby boy has around 66 years of expected lifespan on average, but that's not uniform throughout their lifespan. Death is more probable as an infant, in early childhood, later teenage years, or (for women) in childbirth. Your personal expectancy will go up over time because you've reached a particular age, assuming no notable chronic health conditions.
So, no, they absolutely do not 'get six years'.