The M&C Saatchi founding partner led the Saatchi & Saatchi team that helped to secure an against-the-odds victory for John Major's Tories in 1992.
"Brown has a difficult balance to strike. He has to distance himself from the Blair regime - and that's going to be hard - but he shouldn't be distancing himself from New Labour's achievements.
"So far he's done all the right things and is being very inclusive. His big advantage is that the economy is flourishing and he should focus on that. But people will need reassuring that they're not going to be stung by more tax rises.
"If Brown is going to run advertising, he has to behave like a proper client and approve the work. Margaret Thatcher and Major were very hands-on when it came to the ads and Brown must be the same. Labour has never done memorable political advertising in the past because it has listened to too many voices."
The chairman of Chime Communications and one-time Saatchi & Saatchi managing director was a key figure in Thatcher's 1979 election win.
"Brown's problem is that he has to persuade voters that this isn't a time for change when that's exactly what his opponents are pressing for. He could try to present David Cameron as a boy in a man's job, although these days you're supposed not to be negative. I can't quite see why when sometimes it's the only thing that works.
"What Brown will have to understand is that it isn't about advertising any more. Unless you can come up with something truly memorable, you might as well not bother.
"Brown's record as a steward of the economy can work in his favour. The Tories' problem is that they will have to focus on Brown, even though there's no election to fight. There's no reason for him to go to the country early unless the economy turns shitty. And if he does, people will be asking what he's hiding."
The Delaney Lund Knox Warren & Partners chairman was a member of the "shadow agency" that helped Blair to power in 1997.
"Brown has two challenges. One is to put distance between himself and the Opposition. That's not easy in politics, where everybody wants to occupy the middle ground, especially when Brown hasn't won an election.
"The other is to put distance between himself and Blair. That's something he's already begun to do. This is equally hard given that he was a hugely influential member of the Blair administration. It's important he's seen as a safe pair of hands, trustworthy and statesman-like and not like Cameron, who seems to be saying whatever his market researchers tell him to.
"Doubtless Brown will say advertising isn't important while continuing to do rather a lot of it. The fact is, it can help people form their views and gives you control of what you say because it's unsullied and free of any media intervention."
The founder and creative director of Karmarama, retained by the Conservative Party.
"Brown should be guided by the brains within his party rather than the agency he appoints. Agencies will always go for the easy kill. They're good at telling people that something is cheaper or better. But politics is about much more complex issues. The only way it can work is for the party to give the agency a very concise brief and get the agency to dramatise it.
"Brown doesn't want to be seen slagging off his old cohorts. There's been too much spiteful political poster advertising in the past and we're determined not to do it. It doesn't work.
"Brown's problem is that he's not the fresh new guy who has just arrived. He can't escape he fact that he was close to Blair when Blair was screwing things up."
The former DDB London chairman worked on four Labour election campaigns.
"Political ads have changed enormously in recent years. These days Labour takes its cue from the US, where the emphasis is on direct contact with people, working out who the important voters are and finding the most innovative ways of reaching them.
"There's still a honeymoon period between Brown and the electorate, and the current stand-off between him and Cameron is no guide to what might happen."
The chairman of Engine and a former Tory candidate.
"Brown has got off to a good start. The challenge will be to sustain that and to create a sense that he is distancing himself from Blair. That won't be easy as long as people feel that the NHS isn't working and poverty is as bad ever. It will be the equivalent of a political Houdini act.
"It was telling that Brown launched his leadership campaign behind a misplaced autocue which obscured his face from the cameras. Who is the man behind that autocue? People don't really know. People will take some convincing that Brown wasn't simply the placid gelding at Number 11."