When Diary called to have a chat, Cullum senior, John, was braving the elements in Madrid, where his son has been touring.
He holds a number of other non-exec roles at companies in the South-West, and will be working at least two or three days a month at JBP.
'This is the first time I've worked in PR,' reveals John, although he points out that - courtesy of Jamie - he has plenty of experience of being interviewed by the media.
JBP's clients will be thrilled to hear that Cullum senior's connections could bring some perks, with gig tickets and even the opportunity to meet the musician himself all possibilities.
Cullum senior admits: 'The poor guy's incredibly busy, but he still owes me some student-loan money, so I can twist his arm sometimes.'