All are regional agents including Foxtons, which is also an investor in the business along with Channel 4.
Read MoreSayNoToRightmove leaders urge their 3,000 followers to join Boomin
Estate agency chiefs say they are prepared to forgive the Bruce brothers' 'purple past' to help challenge the established portals.
Read MoreAgency behind SayNoToRightmove rejoins Zoopla, but will it now quit Rightmove?
Acorn, which has four brands and 40 branches across London and the South is tight lipped about whether it will now leave Rightmove.
Read MoreAcorn makes a 3,000 sq ft vote of confidence for the high street
Estate agency group opens its 37th branch in the Kent town of Strood after its opening was delayed by Covid.
Read MoreHomesearch latest: Acorn Group is first chain to pay for challenger portal
Acorn's CEO Rob Sargent says he believes the platform is more than just another place for agents to put their listings.
Read MoreChallenger portals accuse some leading CRMs of ‘obstruction’
OpenBrix founder Adam Piggott says two of the big estate agency CRMs are hindering his and other portals' progress as they sign up agents and try to list their properties.
Read MoreCampaign group to guide members on how to thrive without Rightmove
The Say No To Rightmove campaign has enlisted the help of leading industry trainer and consultant Iain White for the event on 3rd June.
Read More10% of agents have already left Rightmove, says poll of campaigning firms
The Say No To Rightmove campaign, which is leading a group including three other organisations, says a further 7% are waiting for their contracts to end.
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