The publisher of Damian McBride's memoirs is facing questions from police after tussling with a protester as the former spin doctor gave a live television interview.
Iain Dale, of Biteback Publishing, scuffled with Stuart Holmes on Brighton seafront as he tried to get the veteran campaigner's anti-nuclear banner out of shot.
Sussex Police said it was "seeking to interview a man in connection with an assault".
Officers are reported to have arrived at the LBC 97.3 radio studio at the Labour Party conference venue in the city, where Mr Dale has been presenting his regular show.
The barking of Mr Holmes's placard-wearing dog was audible to viewers on ITV's Daybreak as - out of shot - a frustrated Mr Dale grabbed the pensioner's rucksack and physically hauled him out of the way.
As they grappled on the pavement, with the dog joining in, their confrontation was filmed by other members of the significant media scrum which has attended Mr McBride's arrival at the conference.
The protester tried to make the best of the situation, holding up his banner reading "No Nukes - Radio Active Dust Cancer Epidemic" to photographers busy recording the scrap.
After a few moments, the pair separated and dusted themselves down, and the protester went back to trying to edge his way into view of the cameras.
Mr Dale said the protester - a familiar face to conference-goers for 30 years - was an "idiot" and said he had only done "what any self-respecting publisher would do" by stepping in.
But Mr Holmes, originally from Manchester and a veteran of three decades of party conferences, said that after speaking to the police he was considering legal action.