While official national censuses only started in the 19th century, there are examples of cities, areas and parishes which carried out their own surveys of the population before this time.

Norwich was one such city and its 1570 census of the poor and sick remains an interesting insight in the health problems faced by citizens at that time.

Out of a total population of 10,625, the census focused on 2,359 poor and 167 sick and poor living in 790 households, and was carried out in response to levels of disease among the deprived.

Life expectency in 1600 in Norfolk was 45 years of age and even lower in Norwich at just 38.

Dr Victor Morgan, a senior lecturer in English and East Anglian regional history at the University of East Anglia, said: 'The most dangerous year of life is the first year of life. Children were more likely to die during their first year than in any suceeding year.

'Women of childbirthing age also have a very markedly higher mortality rate in pre-modern society.'

The most common condition in the 1570 census was simply the description 'lame', followed by 'sick' or 'very sick'. Other terms used included 'sickly', 'past work' and 'diseased' – the latter was probably used to describe people with syphilis. Surprisingly the word 'ill' was not used at all.

And while only the well-off could afford the most skilled health care, many of the conditions created a demand for lower levels of practitioner including itinerant specialists, oculists, bone-setters and truss-makers.

Before 1668 outbreaks of plague significantly affected Norfolk's population and other epidemic diseases which were prevalent included smallpox, sweating sickness and cholera.

Opium consumption was widespread in the 19th century in the Fens, as noted by Anthony Batty Shaw in his book, Norfolk and Norwich Medicine. Opium-taking was common in King's Lynn, Hilgay, Methwold and Castle Acre where Joshua Love, then in practice there, wrote in 1867 that 'opiates were habitually administered to children while their mothers worked in the field and others minded them'.

Norwich's first medical officer of health, appointed in 1873, noted that children under five made up more than one quarter of the total deaths, attributing this high rate of infant mortality to a lack of food and poor quality food, unclean conditions, ill-ventilated homes and the use of opiates.

Wages were below the national average and often women had to work and either leave the children at home alone or locked out of the house.

Deaths from diarrhoea were commonplace among children – no surprise considering the poor sanitation – and many youngsters who appear on one census fail to survive the following decade to appear on the next.

In the latter half of the 19th century, the census returns help to show just how much of a problem overcrowding was in parts of Norwich, particularly in the courts and yards of the city.

Little ventilation, inadequate toilet facilities and sewerage were prolific sources of typhoid fever and some of the most squalid housing was called 'holes', where homes were below the levels of adjoining streets and next to the river as well as heaps of filth, rubbish and open bins or privvies.

The combing of wool was a frequent source of disease, as was the foul River Wensum – the source of the city's water supply.

And it was no surprise the river was in such as poor state with so many slaughter houses, sewers and fellmongers – who dealt in the animal hides and skins that made the leather for the city's shoe industry – pouring polluting waste straight into the water course. In the King Street area of Norwich, 19 of the yards had neither pump nor pipewater and the people who lived there had to draw their water from the river, into which all manner of foul wastes had been emptied from water closets, butchers, breweries and fellmongers.

Rather than improvements in the field of medicine, historians generally tend to agree that the biggest improvements to the health of the city were environmental – as better housing and sanitation were introduced and slum clearances were carried out. Better food and programmes of vaccination also improved the health of people in the county.

In the latter part of the 18th and throughout the 19th centuries, Norfolk had the highest incidence of endemic bladder stone of any county in England, partly because of the Norfolk and Norwich Hospital's good record-keeping, and its experienced surgeons in this condition, as well as the poor and almost exclusively cereal diet of Norfolk's poorer classes. Health was also affected by occupational illnesses, and disorders included weaver's bottom, twister's cramp – both from the textile industry – game-keeper's thumb, strawberry picker's dropped foot, Brussels sprout picker's wrist, and a whole host of other agricultural conditions, including farmers who were gored by bulls before the practice of artificial insemination was introduced.

But it was not until 1851 that the national censuses first started to ask about health – more specifically whether someone was blind, or deaf and dumb. In 1861 the census started to distinguish if these disabilities were 'from birth' or not, and in 1871 the classifications of 'imbecile or idiot' and 'lunatic' were added.

Ian Cooke, social science curator at the British Library which is currently holding an exhibition about censuses and how they have charted our changing lives, said Florence Nightingale had campaigned, unsuccessfully, to get a question about general health included in the 1861 census.

He said: 'Instead it seemed that what the questions were getting at for blind and deaf people is more about employment, rather than health and trying to trace when it occurred, and also people weren't answering honestly.'

The census of 1871 showed there were 674 idiots or imbeciles in Norfolk, which at one in every 639 people was higher than the national average for England and Wales, which was one in 771 – but by no means the highest in the country.

And with 979 lunatics, the county also had a higher than average proportion of people with mental illness – one in 440 compared to one in 574.

In 1901 'idiot' became 'feeble-minded', perhaps hinting at how attitudes to mental health were changing and this also led to a greater willingness to record senile dementia among the elderly.

Despite these attempts to measure the health of the nation through the census, Edwards Higgs in 'Making Sense of the Census' points out that many of the responses and figures are likely to be inaccurate, as parents and family members were often unwilling to admit that their children or relatives had mental disabilities.

Today, the census results help each area in Norfolk to build up a 'health profile'. This means that NHS services and other associated services, such as social care, can be tailored to best meet the needs of each area's differing population.

For Dr Morgan, the interesting thing about censuses is they are often carried out for a particular reason at the time – for example assessing the population because of worries that a lack of food could lead to civil unrest – but are then able to be used subsequently in many different ways by historians.

He said: 'It has so many facets to it that those who initially set it up could not have even conceived.'

And who knows? Perhaps the results we fill in on our census forms on Sunday will one day prove fascinating to a whole new generation of historians.

TOMORROW – Education