A few months ago I was thrown off a jury. Not because I am an argumentative pain in the backside, which I am. But because I knew one of the barristers. A group of us were being assessed for jury suitability, and he and I both immediately made it clear that our friendship represented a serious conflict of interest. Though I would have attempted to be scrupulously honest and unbiased, it would have been impossible.

I’ve been thinking a lot about this episode in the context of journalism, and in particular the role of the multi-talented and multi-employed George Osborne, who edits the Evening Standard, a newspaper I used to work for. He is certainly the least experienced high-profile editor in Britain, possibly the world, but I wonder if he is also the most compromised.

The salary he earns from editing London’s free newspaper is supplemented with at least eight other roles. Most recently, he was appointed chair of a group of high-profile business leaders who will oversee Exor, the holding company of the Agnelli family, which owns Juventus football club, Fiat, Ferrari and myriad other businesses, including The Economist magazine. He is also a visiting fellow at the Hoover Institution, a dean’s fellow at Stanford business school, chairman of the Northern Powerhouse Partnership and an adviser to BlackRock, the US asset manager, for which he is paid an eye-watering £650,000 a year for working one day a week.

I’ve no doubt that Osborne’s tireless work ethic will ensure he fulfils all of his obligations – with the exception of one. Editor. Because, like me at jury selection, he cannot possibly say that he is not conflicted by personal interest. His honesty, capacity for unbiased decision-making and ability to judge stories without fear or favour are highly compromised by his close – and remunerated – association with some of the world’s biggest companies and most powerful business leaders.

It has been claimed Osborne’s latest wheeze is to offer special clients favourable reporting in return for paid advertising

It’s crucial that readers trust what they are reading. It has been claimed this week that Osborne’s latest wheeze is to offer special clients “money-can’t-buy” positive news and “favourable” comment coverage in return for paid advertising. If true, it would be a partnership fraught with potential mistrust and conflict of interest because readers would not know what was real reporting and what had been paid for; so much so that OpenDemocracy claimed Starbucks had flatly rejected the offer. The Evening Standard group’s commercial director, Jon O’Dowell, has vociferously denied the allegations, saying that the idea the paper was “selling news” was “grossly inaccurate and a wildly misunderstood interpretation of the London 2020 project”, that all commercial content was labelled as such and that “under no circumstances have these clients been guaranteed news coverage for their own ends, nor would they ever be”.

But regardless of the veracity of these latest claims, the dilemma persists for Osborne and the reporting of business stories in his newspaper. We cannot know for sure what is real journalism and what, because of his many jobs, has been ​compromised.

Journalists have always displayed a bias in story selection that has not been made clear to readers in many ways, yet never to the same degree as editor Osborne. His overenthusiasm in the Evening Standard towards companies such as Uber – a significant BlackRock client – is just one of the most notable examples. Yet BlackRock has assets worth more than $2bn (£1.5bn) in pretty much every single major business you can think of.

‘Readers need to know that what they’re consuming is honest.’ Photograph: Mike Kemp/In Pictures via Getty Images

So how can the editor of a newspaper disassociate himself from the fair reporting of a company or individual who is in some way associated with those who pay him extraordinarily generous annual stipends? When editorial conference focuses on the day’s reporting of business news, does the editor of the Evening Standard recuse himself from discussions about BlackRock and Exor clients, or does he helpfully proffer his expertise and inside knowledge? Can he honestly say that his judgment is not compromised?

As I said earlier, I’m not concerned about Osborne’s physical and intellectual capacity to carry out his roles. This is about ethics. Readers need to know that what they’re consuming is honest and unbiased and if there is potential doubt about the content, they should be told.

So when a restaurant critic is friends with the chef or owner of a swanky new joint they – nearly always – own up. When I worked on the Daily Mail I remember being admonished for not revealing in a piece about the internet property company Zoopla that it was part-owned by the same people who owned the newspaper. Richard Desmond, who owned the Daily Express, sometimes asked us to plug one of the new ventures he was helping to back and would always provide a quote somewhere in the piece making clear his link.

Sometimes clarity and transparency are lacking. One newspaper executive incessantly forced us to plug the clients of a PR company that one of his children worked for, for no other reason than that family connection. That kind of murky deal still goes on, but not right at the top. An editor must be seen to be above it all; his or her judgment cannot be clouded by unspoken financial commitments or interests.

Of course they can still show bias – Osborne’s almost daily vendetta against Theresa May is evidence of that. It’s petty, nasty and over the top, but not against the spirit of editorship. Everyone has favourites they shower with praise and enemies they seek to destroy.

As an industry, journalism has never been more vital to society. Yet because of the scourge of fake news it is also one of the least trusted. Osborne’s editorship can only dent that level of trust further. There are many talented journalists who work on the Evening Standard and the paper’s columnists are some of the best-connected writers around. But they will never again be able to write about individuals who are conflicted by multiple interests without knowing, deep down, that their boss is one of the most conflicted of all.

• Grant Feller is a former newspaper executive and media consultant