OnTheMarket agents have been told that membership levels are running ahead of expectations and are “much higher” than had originally been anticipated – with the result that more has been spent on marketing.

Total spend for this year will be over £12m, with at least the same investment planned for next year.

A TV advertising campaign will run, to catch the New Year market.

Progress on membership recruitment is “very encouraging”, OTM boss Ian Springett tells members in an email sent out today.

Reporting on the Letters of Intent programme which began at the end of June, Springett said the target is to reach total support of at least 7,500 offices.

He says in the email: “This will be a significant achievement as we estimate that, if the new members make the same portal choices as our existing members have made, we will have more available UK residential listings than Zoopla – the Tipping Point.

“Progress so far is very encouraging – total support including Letters of Intent is already well over 6,000 offices, of which 90% are contracted offices.

“That is an increase in support of more than30% since launch.

“We will make further announcements as interim milestones are reached on the way to the Tipping Point.”

In the email, Springett also discusses Zoopla.

He tells member agents: “You will no doubt be aware of the persistent negative propaganda being peddled by our detractors in the trade media and elsewhere.

“The context for this is the threat your portal poses to the current and future profitability and stock market value of the duopoloy portals and the soon-to-be-floated online agency businesses which exist on the back of them.

“In particular, Zoopla Property Group will soon announce its financial results for the 12 months to 30 September 2015.

“These are expected to include the eight-month impact on its income of the thousands of agents it has lost to OnTheMarket.com since we launched

“We can expect ZPG to try to persuade investors that OnTheMarket.com is a “short-term event”, that our growth in agent membership has stalled and that we are failing to gain traction with consumers.

“The reality about our growth is that since our launch in January, our contracted office numbers have increased by more than 17% and the pace of our growth is building.”

In the email, Springett also says that October was another record month for traffic with more than 5,7m visits, of which over 60% were from repeat visitors.

In strong defence the ‘one other portal’ rule, Springett says it is “necessary to enable your new portal to enter and become established in a market dominated by two large and powerful media groups, Rightmove and ZPG.

“Rightmove remains by a considerable distance the dominant market leader, so it is unsurprising that over 90% of our members have chosen to retain it as their one other portal.

“Rightmove is now the only portal which has anything close to 100% of available property listings.

“Since Rightmove was already dominant, this does not change its ‘must-have’ status or its pricing power over agents.

“By contrast, Zoopla’s loss of consumer traffic share and member agents is well document and, in our view, supports the recent description of Zoopla in the FT Lombard column as the ‘dispenable number two’.

“Many members tell us that leading Zoopla has had no adverse impact on their businesses and that the number of leads now provided by Rightmove and OnTheMarket.com equals or exceeds the number they were previously receiving from Rightmove and Zoopla.

“Having made a successful and disruptive entry to the market, our next strategic objective is to overtake Zoopla in terms of available UK residential listings.

“From that point we will develop and grow into the sustainably low-cost alternative to Rightmove to serve both agents and consumers better.

“The market does not need three major portals.

“If there are to be two (or fewer), one has agent owned, with supporting your industry and serving consumers as its priorities rather than concentrating on feeding the demands of external shareholders.

“From our daily conversations, we know that the vast majority of independent agents recognise this and want Agents’ Mutual to succeed.”