Sorry I though you were speaking the other way then since you questioned avoidance.
A fair bit.
Which companies? :
Other's also, it's becoming the norm it would seem.
"No man in this country is under the smallest obligation, moral or other, so to arrange his legal relations to his business or to his property as to enable the Inland Revenue to put the largest possible shovel into his stores"
James Avon Clyde, Lord Clyde, Ayrshire Pullman Motor Services and Ritchie v. IRC
"Every man is entitled if he can to order his affairs so as that the tax attaching under the appropriate Acts is less than it otherwise would be. If he succeeds in ordering them so as to secure this result, then, however unappreciative the Commissioners of Inland Revenue or his fellow taxpayers may be of his ingenuity, he cannot be compelled to pay an increased tax."
Thomas Tomlin, Baron Tomlin, in the UK House of Lords case, IRC v. Duke of Westminster (1936) 19 TC 490, [1936] AC 1
Without having access to law books I will have to rely on t-interweb for quotes, but the above look right. That is what I agree with (as do the courts).
Companies dont enter into illegal structures with the hope of them not getting notices. They enter into well planned and thought out structures, which is entirely legal. HMRC can choose whether to challenge them on the grounds that they do not function as intended or it can legislate to avoid that structure working twice.
Cutting deals is a way of guaranteeing revenue for the Treasury. Litigation risk will always exist; getting a large chunk up eliminates the risk of losing a case and gets cash.
The Chancellor himself came out and said “a steady stream of companies that have left the UK in recent years”.
Companies to have left UK: Shire, Brit Insurance, Hiscox, Omega, and Beazley (Lloyd's Insurance companies), WPP, Cadbury, Ineos Runcorn UK, Informat, PepsiCo, Aberdeen Asset Management, Hendersons Ireland, Charter, Regus, Brit Insurance, Wolsely, McDonalds (European HQ), UBM, Kraft Foods, Gallaher, Experian, Catlin, Hiscox and Shell.