The bottom 50% of households in Britain have just £4,400 of cash, property and pensions compared to the £1.2m held by the top 10%, according to an Office for National Statistics report which lays bare the vast disparities in wealth across the UK.

The top 10% of households are now 850 times wealthier than the bottom 10%, the ONS said. It also revealed that half of UK households have just £400 in net cash at hand, compared to the £123,200 in cash balances typically held by the top 10% of households.

Wealthy households are typically in London and the south of England and are three times more likely to be headed by someone with a degree than households in the bottom half of the wealth spectrum, the ONS said.

But the biggest gap between the rich and the poor is not in property but pensions. The ONS found that while the top 10% owned property averaging £340,000 in value, they had built up pension savings averaging £742,000.

The bottom 50% of households had no net property wealth and just £4,000 in pension savings.

The ONS said its research was "the first in a series of short stories looking at the wealth of different groups in society", but the focus on pension wealth comes just days ahead of an expected cut in pensions tax relief in Wednesday's autumn statement mini-budget.

The chancellor, George Osborne, is expected to announce a further raid on pension tax relief for the wealthy by reducing by up to a third the tax-exempt amount people can pay into their pension pots, raising as much as £2bn in revenue.

The ONS report puts the total wealth of the UK, including pensions, property and savings, at £10.3tn. But the bottom 50% of households own less than one tenth of that, compared to the wealthiest 10% who own 43.8% of the country's assets.

The entry level into the top 10% of wealthy households is currently £967,000 in net assets, the ONS said, while membership of the top 1% comes with assets of £2.8m or above.

Nearly one in seven households in the south-east have assets above the £967,000 threshold. In the north-west, the north-east and Scotland just one in 14 households have wealth of more than £967,000.

Physical wealth, in the form of household possessions and valuables, makes up a surprisingly small portion of the assets held by the rich.

The ONS said the top 10% of households have physical wealth of £68,000 compared to the average £18,000 held by the bottom half. More than 95% of wealthy households have a car compared to 58% for the bottom half.

But one of the major signifiers of wealth is the car's numberplate. The ONS found that while just one in 40 cars owned by the bottom half of households had a personalised numberplate, among the rich it is one in seven.