Thousands of people in the South- East suffer from hypertension, or high blood pressure, with many not even knowing they have a problem.

But the condition is serious and medical experts are urging people who believe they might be at risk to get checked out.

Professor Graham MacGregor is chairman of the Blood Pressure Group and author of a new study which urges people to be tested.

He said: "If everyone in the UK with high blood pressure had it controlled to the right level, 21,000 deaths from stroke and 41,000 deaths from heart attacks could be avoided."

Blood pressure increases with age and the Stroke Association estimates that four in ten deaths caused by stroke could be prevented if high blood pressure was controlled.

High blood pressure can also lead to other serious medical conditions such as kidney disease, coronary artery disease and diabetes.

Eastbourne GP Sue Williams said: "Many people are unaware that the risk of cardiovascular diseases develops as you get older and do not realise they may have high blood pressure or be at risk from developing the condition.

"Everyone should know if they have high or normal blood pressure, which steadily increases after the age of 45, as do the risks associated with high blood pressure.

"Monitoring blood pressure at home, as well as regular visits to a healthcare professional for advice and guidance on levels of blood pressure, is an effective way for anyone to assess their state of health as it allows the user to feel more in control of their condition."

People can gain access to automatic blood pressure monitors for use in the home. Alternatively, some pharmacists also have facilities.

Blood pressure is the measurement of the force of blood flowing against the blood vessel and is shown as two numbers on a blood pressure monitor, such as 135/85. High blood pressure consistently measures higher than 140/90.

As hypertension often has no visible symptoms, the only way to know if you are at risk is to regularly monitor your blood pressure.

In the UK alone, there are ten million people with high blood pressure. Half the number of people with the condition are aged 75 and over and about a quarter are middle-aged.

The number of sufferers is likely to increase as the elderly population grows. It is estimated that by 2025, the number of people in the UK aged over 80 will increase by almost half and the number of people over 90 will double.

As well as the elderly, there are other groups at risk of developing high blood pressure. These include those with a family history of the condition, diabetics, black and South Asian people, smokers and people with a high salt diet.

Dr Williams said: "People who believe they may be at risk from hypertension should visit a healthcare professional to find out what their ideal blood pressure is as inaccurate readings may lead to misdiagnosis.

"Once they know their number, they can begin to monitor their own levels. Initially, this should be every day until they have an average reading.

"Blood pressure is higher in the morning and lower in the evening so once an average reading is worked out, tests can be carried out once a fortnight or monthly."

The British Hypertension Society states that between ten to 20 per cent of the population are wrongly labelled with high blood pressure due to the "white coat" condition.

This occurs when patients' blood pressure rises in the presence of a healthcare professional due to the stress of the situation.

According to The World Health Organisation, recommended "normal" blood pressure measurements are 135/85 during the day and 120/70 at night.

Written down as two numbers, the top number of the blood pressure reading is called the systolic pressure. This identifies the pressure in your arteries when your heart is forcing blood through them.

The bottom number, the diastolic pressure, shows the pressure in your arteries when the heart relaxes.

For more details, visit the British Blood Pressure Association web site at www.bpassoc.org.uk or call 0208 8772 4994.