McMullan started his newspaper career at the Newcastle Evening Chronicle, then the Rhondda Leader in Wales, before moving to London to work on the nationals.
The actor Hugh Grant secretly taped him making claims about phone hacking in a visit to McMullan's pub, The Castle Inn in Dover.
In November 2011 he made a notable contribution to the Leveson Inquiry where he not only confessed to a wide range of illegal activities in the pursuit of news but defended them as necessary.
McMullan testified to having undertaken a wide range of illegal or unethical activities to get stories besides phone hacking: bribing police officers, stealing documents, going through celebrities' rubbish bins, and at one point posing as a "teenage rent boy" to entrap a paedophile priest.
"[I]t was hard to think of any dubious news-gathering technique he had not confessed to," wrote New York Times reporter Sarah Lyall, "short of pistol-whipping sources for information."
McMullan owns several properties in Kent, giving his address as the Castle Inn, Dover, when appearing at the Leveson inquiry.
[8] As part of The Castle Inn, McMullan opened a low budget hostel called Dover Backpackers, providing accommodation in dormitory-style.
[13] McMullan is often filmed and interviewed at his pub by TV companies from all over the world including Turkey, India, Europe and Australia about phone hacking and journalism.