Life expectancy has increased 10 years since 1970
It's an interesting thought that we could have achieved all this with clean towels and extra washing, but, off the top of my head, other possible causes include:
Various new vaccines introduced inc flu, HPV, Men C
Huge decline in heavy industry so big decreases in occupational illnesses (like pneumoconosis, asbestosis) and serious injuries.
Decline in smoking.
Compulsory seat belt wearing and safety features in cars.
Technology to improve neonatal survival rates, especially for premature babies.
Increased cancer survival rates due to better screening and treatments.
The NHS and welfare state was only created after WW2, so most adults in 1970 would have grown up without free universal healthcare and access to benefits.
And there are still significant differences in life expectancy between different social classes, ethnic groups and the north/south divide. So, unless white middle/upper class southerners are a lot more concerned with hygiene and cleanliness than everyone else, it's probable that other factors like income, education, housing quality, and access to services are responsible.