Another useful, if basic, point from the Senior Courts Costs Office Guide 2013:

“It is standard practice for the client care letter (redacted where appropriate) to be shown to the paying party. The Court of Appeal has held that it should be the usual practice for a conditional fee agreement (redacted where appropriate) to be disclosed for the purpose of costs proceedings in which a success fee is claimed.”

I wish all law costs draftsmen and costs lawyers were taught this on day one.