Olswang has swooped on the £5m practice of property legend Julian Holy just one month after he was struck off by the Law Society.
The disciplinary tribunal has stayed the strikeout order until Holy has the chance to appeal.
Holy is 55 and retiring, but he has bequeathed his nine-lawyer practice, Julian Holy Solicitors, and its clients to Olswang.
The allegations against Holy are breaches of accounting rules, conflict of interest on loan transactions and "other matters".
Holy said: "I didn't realise that I shouldn't be acting for both sides on a deal... We'll appeal. Counsel is of the opinion that it is completely disproportionate."
Olswang inherits an exceedingly profitable team, with clients such as Rotch Property Group and property magnates the Reuben brothers and Jack Dellal. Holy will oversee the transfer of these loyal clients to Olswang as a consultant.
Olswang chief executive Jonathan Goldstein said he had spoken to Holy's clients and was confident that they would continue to work with the team at Olswang.
Holy said they had all been very supportive, both of the Olswang move and during the Law Society's investigation.
One of Holy's lawyers, Nick Simpson, joins as an equity partner. The other eight lawyers will become associates. The transfer is slated for 1 July. Simpson and five of the lawyers will join the property group, while the other three solicitors are property litigators and will join the litigation team. The property group at Olswang will number 14 partners and 46 other fee-earners, and now accounts for around 20 per cent of Olswang's annual turnover.