A year ago this week, an explosion ripped through BP's Deep Horizon oil rig in the Gulf of Mexico, killing eleven people. The three month battle to cap the well and stop the spill shattered BP's reputation. A year on from the disaster, Lansons Communications held a debate about how BP handled one of the biggest PR challenges ever faced by a British company.

BP made an early, disastrous decision: to deflect responsibility for the disaster to the operator of the rig, Transocean. That may have been technically correct (and this week BP sued Transocean for £24 billion) but meant that BP didn't express a word of sympathy for the victims for four days after the explosion. As a result, BP was on the backfoot from the start.

The other key factor in the PR battle was chief executive Tony Hayward's decision to front the company's media response. Hayward was simply the wrong man to do this. His series of disastrous PR blunders – notably a catastrophic plea that he wanted his life back, after 11 men had lost theirs – fed American anger. And his insistence on going yachting just days after Congress grilled him over BP's performance was an act of immature stupidity.

But BP's biggest problem was reality. Oil gushed into the Gulf of Mexico for almost three months. The greatest communicators in the world wouldn't have changed that stark fact. Oil spills are toxic reputationally as well as chemically: the world remembers the Torrey Canyon, Exxon Valdez and Amoco Cadiz disasters. During the crisis, a quarter of total US media coverage was about Deepwater Horizon. The intensity and duration of that media scrutiny was greater than the coverage of the 9/11 atrocities. Small wonder BP felt beleagured and unloved. 

Speaking at the Lansons event, American body language expert Joe Navarro was dismissive of Tony Hayward's media performance. "You don't ask engineers to do performance", he argued. Yet Ian King, business editor at The Times, took a different view. He applauded the very human response of another technician chief executive, Centrica boss Sam Laidlaw, who cut short a Christmas holiday to respond to a tragedy. Hayward may have done better had he concentrated on leading BP's response, leaving the media and community response to Bob Dudley, the BP executive who grew up on the Gulf coast – and who succeeded Hayward after the crisis was over.

Navarro argued that BP should have built an alliance of the organisations involved, rather than standing alone. I pointed out in the debate that this would have been impossible. Few outside the oil industry had heard of Transocean. And as events proved, the media and politicians were only interested in BP's role: big oil makes an easy target. President Obama shamelessly played fast and loose with reality – theatrically insisting on calling BP by its historic title of British Petroleum. Lansons chief executive Tony Langham said Obama demeaned his office by doing this, but recognised that 'politicians do what politicians do'. 

Ian King was very critical of BP chairman Carl-Henric Svanberg's role in the crisis. He asked why Svanberg didn't more actively support his beleagured chief executive, adding that it was a scandal that the chairman was still in office.

King was generally sympathetic to BP. he admitted that The Times initially treated the crisis as a foreign story, only later recognising its impact. He reflected on BP's dilemma over calls to suspend its dividend in a Times column in June. (At Wednesday's event, he explained how a generation of BP executives including Hayward were seared by the experience of BP's 1990s dividend cut.) And he rightly pointed out that oil companies do dirty and dangerous things so we can run our cars and enjoy our lifestyle. The oil business will never be risk free. Ian added that he never understood why British companies were always so keen to do business in America, given the litigious and protectionist instincts of the land of the free. 

Late in the debate, I pointed out that no one had mentioned social media. This was one of the biggest crises of the social media era. It led Tony Langham to praise BP's use of social media, including a reasonable apology on Facebook for Hayward's disastrous 'I want my life back' plea. Another participant said BP did an amazing internal communications job, keeping BP people informed and reassured. And BP has published a moving film called A year of change, introduced by new boss Bob Dudley, on the first anniversary of the tragedy. 

Langham pointed out the irony of criticising Hayward for insisting on taking the media flak. He asked how many times people slammed company bosses for hiding from journalists when the going got tough. (Remember how invisible bank bosses were during the early stages of the credit crunch?) Yet it takes a formidable comms chief to tell a CEO he or she's not the person to front interviews. And as Navarro said, external advisers are often better placed to do so. 

BP's experience will be studied for years to come. Last month I chaired a CIPR Corporate & Financial Group talk by Andrew Gowers, BP's head of communications during the Deepwater Horizon crisis. I said at the time that many PR people would have been partly relieved, partly disappointed, not to have been involved in this enormous story. We crave big stories – but this was a story that would have devoured almost anyone. 

I'll end with a recent comment from one of our best friends, who works for BP. She said that many BP people were frustrated that the company seemed unable to get its message across during the crisis. I'm sure the company's PR people felt the same way: BP was a company under siege. That siege only lifted when the well was capped. It's easy to look to PR people to solve problems. Sometimes we can achieve that, but reality is always our greatest resource – or weakness. 

Wednesday's event was held by Lansons Communications. It was chaired by Louise Cooper, head of Lansons Live. I was invited as head of PR of a Lansons client.