Lib Dem MP Norman Lamb wants an inquiry into claims the former minister receives £36,000 a year as an adviser to the City of London Corporation.
The Corporation has confirmed the Labour peer had set up meetings with ministers and other work for it since 2006.
Initially Lord Cunningham was employed through Sovereign Strategy, but since September 2007 he has been paid through his own company, Brinkburn Associates.
In a statement the agency said: 'There has been no financial relationship between Sovereign Strategy and Lord Cunningham since he left the board of Sovereign Strategy in mid-2007. This predates Sovereign Strategy joining the APPC in November 2007.'