The business and assets of Churchgate-based Asons were taken over by Coops Law Ltd, sold for £230,000 in March 2017, shortly before the SRA intervened amid concerns about the way Asons was being run.
But the SRA says Irfan Akram, who is not a solicitor and was the sole owner, manager and head of finance for Coops Law, also did not act properly in the takeover of Asons' business.
Following an investigation their ruling states that Akram "used Coops' purchase of Asons Solicitors Limited to undermine and frustrate steps taken by the SRA to protect Asons' clients' interests and the public interest."
They found that Akram had played a significant role in the mass transfer of Asons' client files to Coops without seeking the permission of those clients.
"He knew, or ought to have known, that he did not have client authority to do so," states the SRA.
Akram was also accused of failing to give Asons' clients sufficient information following the closure of Asons and so they were not able to make an informed decision about whether Coops should take over conduct of their cases.
The SRA found that law firm boss also transferred money belonging to Asons clients into Coops client account and then paid some of that cash into Coops' office account for "costs and dispersements" without their permission.
Other concerns raised by SRA included supervision of an employee who sent a generic email to more than 100 Asons clients which enabled them to see the email addresses of all those messaged.
And Akram also paid "lead fees" to a car hire company in a potential legal breach.
Akram, who is not currently working in any legal practice, was fined £20,000 plus £1,350 in costs.
And the SRA have banned him from holding any role in a licensed legal firm including being a head of legal practice, head of finance and administration, manager or even an employee.
In March last year Coops' head of legal practice, Munir Majid, was suspended from acting as a solicitor for six months.
A Solicitors Disciplinary Tribunal stated that he “acted with a lack of integrity and had failed to act in the clients’ best interests.”