Richard Davies' character of "Joe Morgan" appears to be a vague impersonation of 1970's union leader, Clive Jenkins.
Sir Humphrey and Sir Desmond (the banker) discuss "Quangos" at a restaurant. In the United Kingdom and the Republic of Ireland, "Quango" is an acronym for "quasi-autonomous non-governmental organization." Basically, Quangos are non-government workers who oversee the practical duties required by the laws that Parliament passes; the idea being that they are better equipped with the minutiae in the "boots on the ground" aspects of the policy passed. They are paid by the government, but not run by them.
Final appearance of Neil Fitzwiliam as Frank Weisel.