He worked at Phorm for two years and was responsible for building and developing commercial partnerships with publishers and ad networks.
It’s not known whether he has a job to go to.
Prior to Phorm, Barnett was VP for corporate strategy and development at O2.
The ISP-based behavioural targeting company has been dogged by controversy since it launched last year and has endured a number of setbacks, with ISPs BT, Virgin Media and TalkTalk moving away from deploying the service.
BT said it had no immediate plans to deploy the technology, Carphone Warehouse cancelled its contract and Virgin Media said it was delaying use of the technology (nma.co.uk 8 July 2009).
Phorm posted an operating loss of $15m (£9.28m) for the first half of 2009 (nma.co.uk 21 September 2009).
A number of Phorm executives have left the company within the last year, including CEO Hugo Drayton.
Phorm declined to comment.
This story first appeared on newmediaage.co.uk