Today, Boris Johnson's time as Prime Minister will effectively draw to a close with the announcement of his successor, either Rishi Sunak or Liz Truss. While friends and foes may argue about his 'achievements', one thing is certain: his legacy should be the introduction of effective regulation of political advertising, including election advertising.

There was a strange, almost throw away aside in the government's Online Advertising Programme consultation when it was published in June this year. Just two short sentences were devoted to this important subject: "Political advertising - this has not been subject to advertising Codes since 1999. The government believes that having political advertising vetted or censored would have a chilling effect on free speech." In effect, the government seemed to be saying 'we've been free to mislead you without any repercussions for the last 20 years, and we're not going to change that now.'

It's a bizarre state of affairs. There are whole sectors of economic activity which are illegal to advertise, such as tobacco, and others which are subject to strict legal controls, such as financial services and HFSS food. Generally speaking, advertising is subject to legal controls, such the Consumer Protection Regulations, with criminal sanctions attached. For example, Tesco were fined £300,000 by Birmingham Magistrates Court for continuing to claim that their strawberries were half price, when in fact their strawberries had been at that price for so long, that the half price was effectively the normal price.

The law is also supplemented by the self-regulatory regime in the shape of the UK Codes of Advertising, administered by the Advertising Standards Authority (ASA). Any misleading, exaggerated, or unsubstantiated claim will be condemned by the ASA, with the burden of proof being on the advertiser, i.e. the defendant – rather than on the prosecution, i.e. the ASA itself. Just this week, for example, the claim 'kinder to the planet' in an advertisement for Persil was condemned by the ASA because basis for the claim had not been made sufficiently clear and not substantiated on the basis of the full life cycle of the product. These are very demanding and exacting standards, but the advertiser, Unilever, fully engaged in the process of the investigation. They had already submitted to the pre-vetting of their advertisement by obtaining clearance from Clearcast. Furthermore, they then submitted to the subsequent investigation by the ASA and no doubt will now abide by the ASA's adjudication, regardless of how flawed it may be. At no point has Unilever said that the processes of either Clearcast or the ASA will have a chilling effect on free speech. Instead, they have accepted their responsibilities and the jurisdiction of the ASA. (As it happens, I don't agree with the ASA's decision on this matter, as I wrote here.)

But is 'political' advertising different from 'commercial' advertising? Yes, and that's why we have a wide-ranging ban on all forms of political advertising on UK television. We don't want political discourse to be subverted by those with the deepest pockets. But this also means that political issues, with a small 'p', are banned from advertising on TV as well. Many years ago, I tried to help Make Poverty History obtain approval from Clearcast for their ads that argued that the debts of less development countries should be written off. Clearcast were sympathetic, but then Ofcom weighed in and banned the ads on the basis that they were political, because they were trying to influence government policy. More recently, Clearcast found itself having to reluctantly deny approval for ads from Iceland, the supermarket, promoting palm-oil free products to help protect the habitat of Orangutans because the same animated film had previously been used by Greenpeace, an organisation with 'political' objectives.

So ordinary commercial advertising is heavily regulated, as are all forms of 'political' advertising on television, for both Political (with a capital P) parties and political causes (with a small p). It is true, however, that in 1999 the CAP Code, which governs non-broadcast advertising, was amended to remove from its scope "any advertising whose principal function is to influence voters in a local, regional, national or international election or referendum", regardless of when it is published or distributed. This change was precipitated by the furore around the rather silly 'demon eyes' advertisement published by The Conservative Party in the run up to the 1997 General Election.

165 people complained to the ASA that the depiction of Tony Blair with demon eyes broke the CAP Code's rule against portraying living individuals in an adverse or offensive way without permission. While the ASA agreed with the complainants, the process was a bruising one which risked dragging the ASA into an unwelcome and unwinnable political debate. Furthermore, while responsible advertisers like Unilever submit to the regulatory process even when they disagree with the outcome, political parties cannot be relied upon to act with the same degree of self-restraint and maturity.

However, hard cases make bad law. The demon eyes ad was a typical election advertisement: equivalent to 'puffery' in a commercial context. 'New Labour. New Danger' combined with a picture of Tony Blair with demon eyes does not contain a claim that is capable of objective substantiation. If it was a commercial advertisement, the ASA would say that it is 'mere puff', not requiring substantiation.

It is also doubtful that this traditional kind of knockabout political advertisement has ever had a significant impact on the outcome of a general election. Somebody somewhere might have decided not to vote for William Hague, despite their initial inclination to do so, once they'd seen the Labour Party's ad featuring his portrait, with Margaret Thatcher's coiffed hair superimposed. But it seems unlikely. And presumably the follicly challenged Mr Hague was delighted by the image of himself with a full head of hair.

In other circumstances, however, political advertising is more likely to make a significant difference to the outcome of a vote. The paradigm example is a referendum, such as the Brexit referendum of 2016, where people have to make a binary choice between 'yes' and 'no' on a particular issue.

And when a political advertisement around a referendum makes a factual claim which is not mere puff, but one which is capable of objective substantiation, then the departure from the requirements of the CAP Code presents a major problem. Obviously I am referring to the infamous Boris bus and its claim, "We send the EU £350 million a week – let's fund our NHS instead – Vote Leave – Let's take back control."

It's a strong claim, not mere puffery, which is capable of objective substantiation. But it's not just misleading, it's false. While the referendum campaign was still running, Sir Andrew Dilnot, Chair of the UK Statistics Authority said they were disappointed by the continued use of the claim because it ignored the application of the UK's rebate. He said, "The continued use of a gross figure in contexts that imply it is a net figure is misleading and undermines trust in official statistics." In other words, it was an overclaim of exactly the kind that the ASA would routinely condemn in a commercial advertisement.

To make matters worse, Boris Johnson knew that the figure was misleading, if not false, and he did not care. You can watch him dissembling in an interview with ITV's Tom Bradby here.

But the referendum is over, so perhaps it no longer matters? Remainers should 'get over it' and stop re-moaning. Well, no. It does matter, because it is not unlikely that there will be further referenda in the foreseeable future. A second referendum on independence for Scotland remains a possibility. If the post-Brexit status of Northern Ireland cannot be resolved, then presumably a referendum on a united Ireland is also possibility. Writing in The Times on 8th August, columnist Clare Foges even raises the possibility of a referendum on the target of achieving Net Zero by 2050. She argues that stopping Net Zero is the latest objective of Brexiteers like Nigel Farage, who has launched a campaign called 'Vote Power Not Poverty'. His fellow traveller, Steve Baker MP, has migrated from the European Research Group of Spartan Brexiteers to chair the Net Zero Scrutiny Group. Both men have shown that a group that starts on the political fringe can end up usurping conventional opinion.

This raises a rather terrifying prospect. While the ASA holds advertisers like Unilever to account for alleged over-claims for their detergent, politicians will be able to lie with impunity in advertising around a campaign for abandoning the Net Zero target.

In fact, Boris Johnson used the lie on the bus to win the Brexit referendum and then propel himself to No.10 Downing Street. This is in stark contrast to what has happened when he has lied in other contexts and there has been a price to pay. This history of lies and consequences is set out this video produced by Led by Donkeys. In 1988, he was sacked from his job as a journalist at The Times for fabricating a quote for his first front page story. In 2004, he was sacked by Michael Howard, the leader of the Conservative Party, from his role as Vice-Chairman of the party and Shadow Arts Minister for lying about whether he had an affair with a woman who had become pregnant and then had an abortion. In 2019, he had to apologise to the Queen because having obtained her approval for Parliament to be prorogued, the Supreme Court unanimously ruled that his decision was unlawful. Finally, in 2022, after the lies of Partygate and Pinchergate had been exposed, Johnson had to resign as Prime Minister after 40% of his own MPs voted against a Confidence Motion in his leadership, followed by the unprecedented resignation of 57 cabinet ministers, junior ministers and other employees of his government.   

So while truth in advertising matters, apparently in political advertising the freedom to lie is more important and uniquely rewarding, yet risk free. The most important constitutional decision of my lifetime, the decision to leave the European Union, was partly the result of political advertising that was not merely misleading, but false. And the person who did more to propagate that falsehood than anyone else, Boris Johnson, also benefited from it more than anyone else, using it as a platform to secure the premiership. It was not only the most productive lie that he ever told, but it was also one that was free of any negative consequences.

If this lacuna in the regulation of political advertising is not filled, then we risk having our democratic processes subverted again in future. The group Reform Political Advertising argue that election advertising should be brought back within the remit of the CAP Code. They acknowledge, however, that the ASA does not support that outcome, not least because the ASA knows that self-regulation is ultimately based on consent, and there is not much future in trying to regulate political parties that do not want to be regulated. In fact, the ASA is on the record as saying that political advertising should be regulated, just not by them.

In New Zealand, however, the NZ Advertising Standards Authority does regulate political advertising. You can watch a brief explanation of how the system works by their CEO, Hilary Souter, here.  In essence, there are 3 principles for Truthful Presentation in Advocacy Advertising:

1. Advocacy advertising must clearly state the identity and position of the advertiser.

2. Opinion in support of the advertiser's position must be clearly distinguishable from factual information.

3. Factual information must be able to be substantiated.

It would appear that an application of these principles would mean that silly, "puffery", knockabout political ads like 'demon eyes' could continue to run without challenge, but claims like '£350m for the NHS' would need to be substantiated. Which begs the question: If they can do it in New Zealand – and they have done for years – why can't we do it here? It may be that the ASA would need a separate committee to carry out this work in a timely fashion, but there must be a better way than the present free for all.

Johnson's formal departure from office will come tomorrow, Tuesday 6th September, providing yet another example of Enoch Powell's famous aphorism from his biography of Joseph Chamberlain, "All political lives, unless they are cut off in midstream at a happy juncture, end in failure, because that is the nature of politics and of human affairs." And Powell knew a thing or two about political careers ending in failure, so presumably he was speaking from personal experience.

But the person who seems to have the measure of Boris Johnson at a very early age was his school master at Eton, who famously wrote "I think he honestly believes that it is churlish of us not to regard him as an exception, one who should be free of the network of obligation that binds everyone else."

Mr Johnson clearly believes that he should be free from the obligation to be truthful in advertising, an obligation that binds everyone else. And it is for precisely that reason that he – and all other politicians – should not be free of it. They too should be required to substantiate their factual claims.

We need reform of political advertising, and we need it now, before the next referendum that shapes the future of this country for decades to come.