He should apply for a 10-year UK Tourist visa (C-VISIT).

At US$1200 application fee (£ 702 if paid in GBP), it might be the most expensive tourist visa application in the world today. And of course, if the visa is not granted there is no refund.

He will also need to provide a list of every traffic/parking ticket he has ever received, details of every warning/caution ever received from law enforcement, every journey he has ever made outside his country of citizenship (including details of what he did in each place), copies of the last 6 months of statements from every bank account, credit card or investment account he holds and more.