Here are some facts - I leave you to come to your own conclusion.
Dave Hartnett retired recently as head of HMRC. He forced through some 'sweetheart' deals which saved certain companies, such as Vodaphone, many millions in tax and interest. He is now employed by the accountancy firm Deloitte, who acted for some high profile companies.
A parliamentary question elicited the fact that Hartnett had met Deloitte's UK chairman, David Cruikshank, at least 48 times in five years. When a company needed somebody to help them with their tax bill, they called in Cruikshank.
There are plenty of other accountants who had much more expertise in these areas of corporate tax, but it's not what you know.................