Agreed, we have a friend who was a tax inspector. As he observed getting rid of people who regularly recovered more than their salaries, sometimes a lot more, was a curious way to save money!
And no argument from me regarding your second link, perfectly reasonable, and I think that is the key.
Healey's tax the rich until they squeal at 98%, or whatever it was, may have played well to the far left. In reality it amounted to 98% of b****r all, as it was mostly avoided by one means or another. Set it at a reasonable level and I suspect most will pay up, then you can concentrate your efforts on chasing down those who wont, with lots of publicity and hefty fines, seizure of assets and or imprisonment as an encouragement. I think it is unrealistic to expect that you can ever close down every avenue of avoidance, if you can reduce the number inclined to do so in the first place you have a much better chance to Hoover up the remainder. I think it is quite wrong to universally demonize the rich, and assume that they are all intent on Jimmy Carr type schemes. Of course there are those who fit that stereotype, but I suspect most don't, and many already distribute huge sums through various philanthropic activities.