Both Rightmove and Zoopla have said that they are taking down properties very promptly where they are asked.

Eye contacted both portals after claims that agents’ properties are still appearing on both Rightmove and Zoopla, even when the agent has joined OnTheMarket.

For example, the Financial Times said that on Monday, Savills listings were appearing on Zoopla although it had stopped the data feed to the portal. Savills, a founding member of Agents’Mutual which launched OnTheMarket two days ago, has come off Zoopla, choosing Rightmove as its “one other portal”.

The FT quoted OTM as saying there was no “grace period”for its member agents to remove property details from a third portal.

OTM told the paper: “If members do not meet the commitments they will be in breach of contract and they will be removed from the portal if they have not instructed any of their other portals to remove their properties.”

Eye has also this week been told of instances where OTM agents’ properties still seem to be on Rightmove and Zoopla.

A spokesperson for Rightmove yesterday told us: “If an agent chooses not to renew their contract with Rightmove their properties are removed when the contract expires.

“If they ask for their properties to be taken off the site before the contract ends they will be removed by Rightmove on the date requested.”

A spokesperson for Zoopla said: “As soon as we receive instructions from members to remove their properties we do so with immediate effect. Any claims to the contrary are wholly false.”

While it remains far too early to start serious number-crunching, City analyst Jefferies – which acts as corporate broker for Zoopla – had a stab at it on Monday, as reported on Eye yesterday.

It said that: “We have searched the listings of all three portals across all 32 London boroughs for two and more bed residential properties for sale and rent: Zoopla currently displays 73,989 listings, OTM 9,243 and Rightmove 51,860.”

In fact, its full-length note to investors is rather more interesting than that, making clear that it may well have under-estimated Rightmove’s presence in London, because it did not take into account the fact that Rightmove limits search results to 1,000 if a large search area is selected.

In its longer version, Jefferies acknowledges this, saying: “We note that Rightmove limits its search results to 1,000 properties.” It reckons that Zoopla has lost no more than 9% of its London listings.

Yesterday, Zoopla had its second consecutive strong day on the stock market. The shares bounced by 20p, up 12%, ending at 190p.

Rightmove’s share price also rose strongly by 4%, closing up 93p at 2,440p.

Another big riser was Foxtons where following its trading update the shares put on 19p for an increase of almost 12% to close at 178p.