In May 1992, Horrocks was appointed editor of BBC Two's social affairs programme, Public Eye, a position he held until he launched Here And Now, a current affairs magazine intended to capture high audience figures, in January 1994.

He was executive producer of Brits, True Spies, Smallpox 2002, The Day Britain Stopped, Dirty War and of the documentary trilogy The Power of Nightmares.

[2] In April 2009, he replaced Nigel Chapman as Head of the BBC World Service and was responsible for the overall editorial leadership and management, a post in which he remained until 2014.

[7] In 2018 Horrocks took part in a Parliamentary hearing on value for money in higher education, with MPs criticising the level of pay of vice-chancellors and asking them to justify their salaries.

He later issued a letter of apology and stated: "I sincerely regret that my careless language caused offence or hurt".

[10] The following month, the OU's branch of the University and College Union (UCU) passed a vote of no confidence in Horrocks, or his plans.