Kerr has worked as a freelance journalist since 2004, but worked closely with Sheridan during his five years as press officer for the SSP. Sheridan left the SSP to found his own party - Solidarity - with fellow socialist MSP Rosemary Byrne last month. Kerr is employed by the party.
Sheridan famously won £200,000 in a defamation case against the NotW, following allegations about his private life, earlier this year. But last weekend the paper released a video allegedly showing Sheridan admitting some of the charges.
Kerr organised Tuesday's press conference, where Sheridan vowed to ‘take on' the tabloid, claiming the video was faked - this is denied by NotW.
Sheridan's most recent media adviser Jim Monaghan made headlines last month, when emails that seemed to suggest he believed some accusations against Sheridan were leaked.