Zoopla has revised its expectations for how many house sales will have been lost this year but has warned there is still an imbalance between supply and demand.

Analysis by the portal found sales agreed have increased since lockdown was eased but said this was mainly from pent-up demand before the pandemic, with the Stamp Duty boost only really helping buyers in London.

It estimates that 124,000 sales will be lost over 2020 as a result of the market closure.

The property website previously said in April that more than 400,000 sales were delayed due to the property market closure between March and May.

It initially predicted a 30% decline in sales but its latest forecast suggests it would be 15%.

Knight Frank has been more pessimistic by warning that 500,000 sales will be lost.

That was all before the market reopened and the Stamp Duty holiday was announced.

Since the market reopened, Zoopla claims, new sales agreed are running 28% above pre-lockdown levels but are down 20% annually as of the end of June.

Zoopla estimated that returning buyers account for 80% of levels that would have been expected over this period in 2020 had the pandemic not struck.

It said a lack of supply and high level of demand isn’t helping sales and is pushing up house prices by 2.7% annually across the UK to £219,500 on average and 2.3% year-on-year among the largest 20 cities in the UK to £255,300.

Zoopla said supply since the start of the year is lagging 20% behind compared with 2019, while demand is 25% higher.

It is too early to assess the full impact of the Stamp Duty holiday but the portal said new sales agreed are up 27% over two weeks in London, but warned other regions may not have as big a boost as prices are lower.

Richard Donnell, research and insight director at Zoopla, said: “Covid-19 and the lockdown have shifted the dynamics of supply and demand across the housing market.

“The staggered reopening of housing markets across countries and the added impetus from the Stamp Duty holiday mean we expect buyer demand and new sales volumes to hold at current levels over the next two months.

“The net result will be continued support for house price growth at current levels over the second half of the year.

“We expect rising unemployment to weigh on market activity over the final quarter of 2020 and into the first half of 2021.

“The impact on pricing looks set to be pushed into 2021 as a result of sizeable Government support for the economy.

“Further support cannot be ruled out while forbearance by lenders, and the availability of the mortgage payment deferrals, which can start up until the end of October for three to six months, is likely to limit the scale of downside for house prices.

“Much depends on how businesses respond to the outlook and their decisions on staffing levels and the knock-on impact for unemployment.”

The boost in sales agreed is reflected in data from NAEA Propertymark’s June Housing Report.

Members reported the average number of sales agreed per estate agent branch stood at 10 in June, double the amount recorded in May when there were five sales recorded per branch.

One in 10 properties sold for more than the original asking price, which is the highest recorded since February 2016 when 11% sold for more, NAEA Propertymark said, while 57% sold for less.

NAEA Propertymark’s research also found the number of house hunters registered per estate agent branch rose by 10%, increasing from 344 in May to 379.

This is also up from 305 in June 2019.

The number of properties available per member branch stood at 37 in June, level on last year but increasing from 35 in May.

Mark Hayward, chief executive of NAEA Propertymark, said: “It’s positive to see the market continuing to boom after the Government re-opened the property market in May.

“Usually we’d expect to see a lull in activity during the summer months, however, with estate agents following new social distancing protocols and both demand and sales soaring, it seems we’re in for a busy summer.”