Chris Sier, the ex-policeman who has been on a 10-year mission to shine a light on fund trading costs, wants to talk about his lucky cufflinks.

"Let me take you back to 2008," he begins the story. "I was a technology consultant, helping fund managers manage their data. In 2010, I was asked to write a report for the government on the automation of trading in financial services. I used a mutual fund as a case study.