All three main property portals have said that they crack down hard on ‘portal juggling’ and will continue to do so.

All three also insisted they have strong detection systems in place to prevent agents gaming the system.

The practice of ‘portal juggling’ has been under the spotlight on EYE, and also elsewhere on the internet.

The claims are that agents – with some online agents particularly accused – game the system by re-entering properties as new.

Sometimes, it is alleged, this is done to disguise price reductions. Or it is done to disguise how long a particular property has been on the market. Or it is done to make it look as though an agent has plenty of new instructions.

One poster on EYE recently told of a property apparently new on the market this early autumn, when the pictures showed snow.

A spokesperson for Rightmove told us that Rightmove’s reload detection technology stops agents trying to re-introduce a property, and that “greatly reduces the number of cases”.

The spokesperson said: “Trying to reload properties as new is not something that we tolerate and our data quality team take it very seriously.

“At Rightmove, we continue to ensure that users are seeing the most accurate information and that agents are operating on a level playing field.

“That’s why we created our reload detection technology and are constantly looking at new ways to make it even better.”

Rightmove send outs both new properties and price changes on its property alerts.

The spokesperson said: “This information is also updated on the property listing on the website itself. The ‘date added’ to site is also on all property listings.”

At Zoopla, a spokesperson said: “We have automated anti-gaming processes and detection methods in place to prevent re-listed properties from appearing as ‘new’ and triggering an alert.

“Where agents attempt to circumvent these processes, we take the issue extremely seriously.

“We have a dedicated compliance team to police this and a ‘Report Listing’ button on every property listing, where users can (and do) alert us to any discrepancy.

“This behaviour by a small number of agents is not commonplace and not specific to any one type of agent.

“However we make a point of following up with any agent who has multiple complaints.”

OnTheMarket does not show when properties were first listed or price changes, but a spokesperson made it clear it is aware of the problem.

She said: “A robust set of procedures were installed prior to our launch in January to ensure we could quickly identify any attempt to re-list properties as new.

“Any suggestion of ‘gaming’ highlighted within our internal procedures or externally from the estate agent community will always be thoroughly investigated.

“Our measures in place are constantly revisited to ensure they adhere to our high standards and remain robust.”