On Monday, the content provider Boris Johnson positioned a typically triumphant column in the Telegraph. Having had a hail of multicoloured children’s swimming pool balls flung at him by suddenly energised disabled people in Manchester, the mischievous reaver explained to Telegraph readers that people throwing eggs and calling the Conservatives scum are the same as people who victimise Jews, Gypsies and homosexuals.

Then the one-time window-smasher declared that Tory haters merely transfer their own unhappiness on to the undeserving and innocent scapegoats of the Conservatives, before taking a sideswipe at Theresa May’s pre-Bake Off immigrant bashing. The Bullingdon golem, his masters’ enemies suitably roughed up, has swallowed his sub-lingual tablet and runs rampant in the Prague ghetto of the Tory press, bumping into potential leadership candidates and trampling their best-laid plans under his hooves like Japanese children.

But the mayor of London’s comparing of egg-smeared Conservatives to the systematically eradicated victims of mass pogroms is so blinkered, insensitive and distasteful that it demonstrates perfectly why Johnson himself is scum; and why the calculatedly crumpled operator should be chained to a rock and have hot eggs pounded into his pie face for all eternity, waking each new morning to find yet more egg leaking endlessly into his eyes, discharging directly from the smelly anuses of perpetually hovering hen harriers, like some slapstick Prometheus of low-rent legend.

The press would have us believe Labour is swallowing its tail, a socialist serpent, coiled in U-turns; and Tom Watson totters unsteadily, like a pile of CD singles by forgotten pre-Britpop bands – Mint 400, Bivouac, the Voodoo Queens – stacked precariously in a cluttered polytechnic entertainments officer’s workspace, somewhere in the north-east, circa 1991.

In the light of this disarray, Johnson’s can’t-be-arsed column is typical of the confidence engulfing the unshackled Tories rampant. And who can blame them? They seem free to operate beyond the law, beyond truth, beyond accountability, beyond good and evil. When I record my multiple Bafta and British comedy award-winning standup routines for television or DVD, lawyers check the content. They are taking notes in my current run of theatre shows this week, where I prepare material for my next TV series, and I am enjoying the last few days of playing with phrases I know will not pass the BBC’s stringent legal checks.

It is unlikely, for example, that I will be able to say the man Labour MP Emily Thornberry saw flying an England flag from his Rochester home was “obviously racist” because he “looked really racist”, even though contained within the bit is an implicit critique of my own liberal prejudices about the appearance of a Kentish van driver. The irony-aware theatre audience understand this, but the problem with the BBC is that pretty much anyone is allowed to watch it, though the culture secretary is sure to sort this out soon.

But practical restrictions can become creative opportunities in themselves. In 2008, I wrote a parody of the then Celebrity Big Brother host Russell Brand dealing with racism on the show: “Ooh there’s some bad racism and stuff like that going down today and no mistake, my liege. It’s made my winkle go right small, it has. Oh yes it has, yeah, and my ballbag, my ballbag has gone up my bum. Here’s H from Steps.”

Lawyers for the DVD release of the live show it appeared in said it was so close to Brand’s actual speech that I might be accused not of satirising him, but of misrepresenting him. Rather than cut the bit, I inserted an improvised interview where Johnny Vegas took me to task for feeling I had the God-given right to misquote people for comic effect. In an endless feedback loop this clip now appears, shorn of its parent show, on YouTube, where members of the public mistakenly perceive it as an unofficial exposé of my own insufferable arrogance.

Other legal issues have been more easily circumvented and I’ve often been able to hang on to the basic thrust of contentious routines by the substitution of a single word, such as “infer” instead of “read” (in a bit about perceived criticisms of me in a panel show comedian’s autobiography), or by changing “the Conservative party” to “some people in the Conservative party” (in a piece about their use of the slogan “If you want a nigger for a neighbour, vote Labour” in Smethwick in the 1964 general election).

Hilariously, in 2009 I was required to cut a routine imagining al-Qaida training dogs to fly planes, out of respect for Islamic sensitivities regarding dogs, only a few months before it was revealed that the same terrorist group had been experimenting with explosive-packed canine suicide bombers, irrespective of cultural taboos. You couldn’t make it up! It’s political correctness gone mad!!

Essentially, while I am allowed to exaggerate for comic effect (if it is considered by the lawyers that the exaggeration is obvious and clearly authored by an unreliable and biased character, ie me), I am not allowed actively to lie. And it struck me as strange, as I watched the eggs rain down on Conservatives this month, that my standup comedian’s lowly standup comedy routines are held accountable to higher legal standards of truth and decency than, for example, a prime minister’s conference speech.

Cameron’s repeated smearing of Corbyn in Manchester, for supposedly saying 9/11 was not a tragedy, when he obviously did the complete opposite, is the case in point. Paradoxically, while the BBC can broadcast Cameron’s lying speech in full, without any critical analysis or disclaimers, if I had written the same comments in a standup comedy routine the lawyers would tell me it could not be transmitted.

The Tories seem free to operate beyond the law, beyond truth, beyond accountability, beyond good and evil

I suppose somebody in Conservative central did the maths and decided that the long-term benefits of associating Corbyn with a dishonestly decontextualised phrase about 9/11 outweighed the risk of Cameron himself being perceived as a fundamentally deceitful and manipulative liar; and that a sympathetically biased, or cowed and fatally compromised, media were unlikely to hold the prime minister to account for his lies.

To be charitable, perhaps Cameron genuinely thinks that, for the long-term good of the UK, Corbyn must be discredited at any cost, and that truth, ethics, decency are justifiable collateral damage. This is the kindest thing you can say about the unprecedented depths of dishonesty the prime minister sank to in his conference speech. And then Boris Johnson wonders why people threw plastic balls at him. If I’d been there I hope I would have had the courage, fortitude and moral backbone to have thrown my own [word deleted under legal advice].

Stewart Lee’s A Room With a Stew is at Leicester Square theatre, London WC2 until 8 Jan.