Three English towns have been studied in considerable detail.
Ipswich in south-east England has the lowest CHD mortality: 89 for men and 79 for women (Standardised mortality ratios (SMR), national average =100)
Stoke in the midlands has a CHD mortality SMR of 115 for men and 128 for women.
Wakefield in Yorkshire in the north of England has CHD mortality SMR of 115 for men and 137 for women.
We can see that mortality rates in Ipswich were below the national average, while those in Stoke and Wakefield were above the national average.
The study included data collection by house-to-house questionaires to establish dietary patterns. The expectation was more food, more fat, more sugar, more calories as we move north-west from Ipswich. In reality the opposite was determined. The residents of Wakefield in the north had the lowest nutrition intakes, most notably of fat, carbohydrate and total energy.
Cade JE, Barker DJP, Margetts BM, Morris JA. Diet and inequalities in health in three English towns. Brit Med J 1988; 296: 1359-1362.
So, what is the reason behind the mortality gradient in the UK from the south-east to the north? Could it be something to do with the location of the towns and the climate rather than collective human behaviour? Could it be the greater sunshine exposure of those living in Ipswich in the southeast that gives the advantage?
I would not advocate lack of sunshine as being the cause of death from CHD, but it increases suceptibility. More sun is a good thing.