Insolvency barrister John Higham QC joined the London firm in April. But he continued to be retained by a rival firm, which he refuses to name, working for the co-defendants in a piece of asset-tracing litigation in the Cayman Islands.
Now, Stephenson Harwood's head of litigation, John Fordham, is leading a team advising the other co-defendants.
Higham says he has not spoken to lawyers at Stephenson Harwood about the case since he joined, and the only discussion has related to the Chinese wall arrangements.
The only way he has been able to take the case is that as a consultant, he will not benefit from the fees brought in from the other co-defendant.
Next year it is understood he will be made an equity partner.
This kind of arrangement is common in specialist chambers. But Higham says he has found that Chinese walls are enforced much more rigorously in law firms.
Higham says: "The arrangement that both clients have agreed to is that I can continue to advise.
"The way it is done physically is that I don't have papers related to the case here. They are kept at the other firm of solicitors, and that's where I give my opinions.
"Stephenson Harwood's papers related to the case are held on another floor and I have given an undertaking not to enter that room.
"They also have a security system which means I don't have access to emails in relation to that matter.
"I must not discuss the case with Stephenson Harwood."