Tony Abbott and Boris Johnson (Images: AAP/Joel Carrett, AP/Dennis Van Tine)

British Prime Minister Boris Johnson has taken a great deal of flak for appointing Tony Abbott as an adviser to the UK Board of Trade -- an appointment confirmed over the weekend.

So why is Johnson prepared to lose political capital for the sake of giving an (unpaid) role to Abbott? Brexit is at the heart of it -- along with a host of libertarian and unaccountable think tanks.

The path from Johnson to Abbott goes primarily via an influential Tory operator, Daniel Hannan, who is an ex-Conservative Member of the European Parliament and a leading Eurosceptic figure.