I would say your points are all pretty spot on, but you don’t mention ‘know your client’, I find this although not fool proof helps, especially if they have to be looked in the eye to tell all at the outset, saves embarrassment later on for all, and in order of importance I would rank as follows:

1. Know your client
2. Be forceful and controlling in character (paranoid can sometimes help here, but not always)
3. Be technically very competent
4. Do the legwork thoroughly (HMRC will)
5. And if you really want your client to sit opposite the Revenue then prepare your client, then prepare them again, then tell them to say nothing unless you indicate they can

Lets be honest, the new combined Revenue and Customs is a massive machine with good intelligence, Customs have always had the edge at investigatory work, and now this is being shared.

I have previously, before the merger, had joint investigations with both Revenue and Customs inspectors, and I know who you have to watch out for, Customs are sharp, their methods ruthless and their data extrapolation abilities pretty darn good, and now they are sharing techniques

A Revenue favorite I have always found is the pregnant pause, that time between questions, or more commonly an answer from your client where the inspector goes quiet, they may write for a while then look up at the poor, terrified tax payer, but what ever happens at all times never feel the need to fill a pregnant pause, if anything let your advisor fill it by concluding the meeting, this will spur the inspector back into action.

HMRC now employs accountants, and I have met a few across the table, so my advice to the accountants defending their clients consider taking in with you either a very experienced accountant or better still an experienced chartered tax advisor, these meetings are not always unpleasant, but if they are you will be relieved you brought in the big guns!