On Thursday, celebrity gossip newsletter, Popbitch, announced that Mr Johnson had “tacked” his mobile number “on to the bottom of an old press release” that he posted on the internet in 2006, while serving as the Member of Parliament for Henley, and Shadow Minister for Higher Education.
The personal contact details, which are still online, appear to be the ones currently used by the Prime Minister
In its latest update, Popbitch told readers playfully that “the 3M’s number is common knowledge”.
“Critics say it’s highly irresponsible that any 7om, Dick or Harry could just freely add the PM on WhatsApp and strike up a chat,” it added.
The revelations comes after Government officials were forced to deny claims that Mr Johnson had been advised to change his number amid concerns over Downing Street security last week.
Lord Ricketts, a former UK national security adviser, warned that hostile states and criminal gangs may already have access to the Prime Minister’s number.
The crossbench peer said he assumed that changing mobile phone numbers upon taking the top job in No.10 would have been an "elementary security precaution” against enemies with "sophisticated cyber capabilities".
Labour’s Rachel Hopkins also criticised the Prime Minister’s use of the mobile number, claiming its availability online had serious implications for security, lobbying and the risk of blackmail.
A spokesperson for Downing Street declined to comment on Popbitch’s story on Thursday evening.