Hermod/Water seeks its own level.
I suppose any tax advantage they get in a London HQ will quickly be diluted with the perks and salaries for the suity set and whatnot in rental fees.

"This is captain Sergio Marchionne speaking. We are now circling London, at 17,000 ft altitude, it is a beautiful crisp morning today; we will be landing at Heathrow in approximately 15 minutes and are experiencing some delay due to particularly heavy traffic at the airport this morning. Welcome to the home of 17,000£ monthly mortgage fees."