British businesses continued to invest and consumers carried on spending in the months following the Brexit vote, defying predictions that a wave of uncertainty would hit economic activity.

In the first official estimate of how firms’ spending fared after the referendum, the Office for National Statistics said business investment rose 0.9% in the July-to-September quarter. That was only a small slowdown from 1% growth in the previous quarter and beat forecasts for 0.6% growth in a Reuters poll of economists. The figures echoed business surveys suggesting companies have shrugged off the shock of the referendum result for now.

The ONS confirmed its earlier estimate that GDP expanded 0.5% in the third quarter, only a small slowdown from 0.7% growth in the second quarter and stronger than most economists had predicted in the immediate aftermath of the referendum result. But there were warnings the brunt of the Brexit vote would be felt next year as the weak pound stokes inflation and as negotiations over leaving the EU begin.

Providing more details of the third quarter in Friday’s update, statisticians said consumer spending continued to be the main driver of economic growth, fuelled by rising household incomes.

There was also a contribution to growth from net trade – the difference between what the UK exports and imports. That came as imports fell but exports grew, probably helped by the weakness of the pound since the Brexit vote, which makes UK goods more competitive in overseas markets.

But the data also confirmed earlier estimates showing that the construction sector had fallen into a technical recession, contracting for two straight quarters, while output was down for manufacturers and the wider industrial sector.

The ONS said that since the referendum in June, GDP growth had been in line with recent trends, suggesting “limited effect so far” from the referendum.

Darren Morgan, head of GDP at the ONS said: “Investment by businesses held up well in the immediate aftermath of the EU referendum, though it’s likely most of those investment decisions were taken before polling day.

“That, coupled with growing consumer spending fuelled by rising household income, and a strong performance in the dominant service industries, kept the economy expanding broadly in line with its historic average.”

Economists were quick to warn the recent pace of growth would be hard to sustain. The government’s independent forecasters, the Office for Budget Responsibility, predict growth will slow to 1.4% in 2017 from 2.1% this year as business investment slows and as incomes are squeezed by higher living costs. Inflation is expected to pick up because the weaker pound makes imports to the UK more expensive.

The data company IHS Markit said its surveys pointed to the firms’ and households’ resilience continuing into the final quarter of this year. But it too was cautious about the year ahead.

“For the moment, the data suggest that the economy has exhibited greater than anticipated resilience in the face of headwinds such as Brexit worries and rising prices. However, it seems likely that growth will slow further in coming months as these headwinds intensify,” said Chris Williamson, chief business economist at IHS Markit.

Ruth Gregory at the consultancy Capital Economics said importers and retailers would likely absorb some of the increase in costs from the weak pound, ensuring that the squeeze on household incomes is not too intense. Low interest rates would also help support consumers, she said.

“With ultra-accommodative monetary policy continuing to support spending and discourage saving, we don’t think a sharp slowdown in spending is on the cards.”

A leading thinktank warned this week that the combination of rising inflation and weaker pay growth as Brexit unfolds will mean UK workers face the longest squeeze on their pay for 70 years. The Institute for Fiscal Studies said that the recovery in real wages – pay adjusted for inflation – will now be so slow that by 2021 they will still not be back to their 2008 level before the global financial crisis hit.

For now, however, the ONS figures showed consumers remained the biggest driving force behind GDP growth. Household spending rose 0.7% in the third quarter, down only slightly from 0.9% growth in the second quarter.

Kallum Pickering, senior UK economist at the bank Berenberg said: “Rather than postponing spending decisions amid the heightened uncertainty following the Brexit vote, good fundamentals – a strong labour market, rising house prices and improving credit conditions – supported a continued expansion in household spending.”