Paul asked:

Has anybody personal experience with change management in very large organisations? What are the hard-and-fast rules? 

Paul,
Some time ago you were asking for what we had re change mgt. I think the 8 step process recommended by Prof. John Cotter makes a lot of sense (see below).

8 step process
• Establishing a sense of urgency
• Creating a guiding coalition
• Developing a vision and strategy
• Communicating the change vision
• Empowering others to act
• Creating short term wins
• Consolidating gains and producing even more change
• Institutionalising changes in culture

This I have extracted from a presentation that I gave on Leadership & Change for a Knowledge Sharing Session in MR in May 2003 (see below in case you find any of the other bits/ context helpful).
 

Robert de Verteuil, Main Roads