He told Reuters: “We have lost our way in sales and lettings … she (Platt) did the honourable thing and decided to step aside.”
Platt had taken personal responsibility for reviving the company’s main sales and lettings business in August.
It comes after Britain’s biggest lettings and estate firm warned its full-year profits would be hit by weakness in its UK sales and letting business, particularly in London and the South East – an announcement that sent its shares plummeting about 20%.
Profits are expected to drop by 22% to £65 million in 2017, down from £83.5 million the year before.
The UK housing market has become subdued in recent months, hit by uncertainty over Brexit and low income growth.
Credit rating agency Fitch has warned that the UK market will be among the weakest in the world this year.
The market is also slowing because of affordability constraints – housing costs have more than doubled in the past 60 years to almost a fifth of household incomes.
Long said the organisational changes made by Countrywide, along with the cooling property market, led to it losing market share to other traditional competitors.
“There has been a lot of changes in the organisation and I think that caused disruption and a negative impact in terms of our ability to sell homes,” he added.
Long said the sales and lettings area had “lost focus” and that a key priority will be to “implement changes that will enable this area to start delivering once again”.
“Working together with this experienced executive team I feel confident we can return the business to profitable growth,” he stated.
Countrywide has yet to announce a replacement for Platt, who has been in charge of Countrywide since 2014.
Platt, a former Bupa and British Airways executive, was a rare appointment to the helm of a big estate agency group because of her background outside the industry.
“Since joining in 2014 I have worked hard, within a difficult market, to structure a fragmented business into one set for success,” said Platt. “I believe those actions will serve Countrywide well in the future. However, the time is now right for me to step aside. I look forward to seeing the business build back and return to growth.”
Long will act as executive chairman until a successor is appointed, while Paul Creffield, previously managing director, commercial development, has been appointed group operations director. Creffield’s remit also includes responsibility for the sales and lettings division.
DealMakerz thinks Countrywide needs an injection of new, entrepreneurial blood to see it through the next few years.
The estate agency industry is facing significant challenges thanks to the slowing housing market and a proposed ban on letting fees.
Traditional agents are having to invest in technology, close branches and slash their headcount to cope with the growing threat from online agencies like Purplebricks.