What is the test for an attorney to be presumed to have knowledge of confidential information from a former representation?

When a substantial relationship has been shown to exist between the former representation and the current representation, and when it appears by virtue of the nature of the former representation or the relationship of the attorney to his former client confidential information material to the current dispute would normally have been imparted to the attorney or to subordinates for whose legal work he was responsible, the attorney's knowledge of confidential information is presumed. (See People ex rel Deukmejian v. Brown, supra, 29 Cal.App.3d at pp. 155-156, 172 Cal.Rptr. 478, 624 P.2d 1206.)