ABC / ABCe

Owned by the media industry, ABC independently verifies and reports
on media performance, providing a major trading currency for media
buyers and owners across print, events, digital and evolving platforms.

ABCe provides independent auditing and certification of a wide range of digital media including web, email, video streams, ad networks and digital TV. 

ABCe Associate

In addition, because ABCe data is prepared to industry-agreed standards, it delivers a common, comparable currency to media owners and buyers. ABCe is an industry-owned, non-profit distributing organization. All profits are invested back into the business for the benefit of the industry.

http://www.abc.org.uk