My firmly held conviction had always been that those standup comedians who seek to talk about subject matter outside of the banal observational Live at the Apollo-style nonsense should have absolutely nothing to do with any political party, no matter how much they might support that party’s policies. I am aware that others might not agree. I seem to remember that Eddie Izzard once had plans to run as Labour’s candidate for mayor of London, or maybe he was planning to run as mayor of 11 different cities on 11 different consecutive days in aid of Children in Need, I don’t now recall. Either way, that scheme seems to have gone away while Jimmy Carr sits in the Storting, the Norwegian parliament as an MP for the centre-right Kristent Samlingsparti, the Christian Unity party, (though this may be part of a strategy by Carr to try to gain some kind of Europe-wide parliamentary immunity, who knows?). But the reason I believed we comics had to steer clear of any and all parliamentary groupings is that we have a sacred duty to Speak Truth to Power (I also shout obscenities at fishmongers but that’s something else).

Throughout history this has been the holy role of the jester, the fool, the licensed clown, from whom all of us who stand in front of the microphone descend. There are striking examples all through the world and we see echoes of this history in today’s comedy performers. The Wolof people of Senegal had an entire caste, the Noole, who served in the royal court as jesters – although they were at the bottom of the caste system, they could say unpleasant but true things to the ruler without being punished. There is a 15th-century Ming dynasty description of a jester that captures our art, “for besides always hitting the mark with his gilded tongue, he would unleash his body and fling his limbs around, drumming his feet and flapping his tongue; he was steeped in wisdom” (that is coincidentally almost word for word a four-star review of my 2013 Edinburgh fringe show). Then, in the 16th century, Martinelli was the first actor known to have performed as Harlequin. He became a favourite of Henry IV of France, to whom he would address “insolent monologues”. Among the Native American Lakota people, the heyoka is a contrarian, satirist or sacred clown. The heyoka speaks, moves and reacts in an opposite fashion to the people around them: he will ride a horse backwards, wear clothes inside-out or speak in a backwards language. A unique example is the famous heyoka sacred clown called “the Straighten-Outer” who runs around with a hammer trying to flatten round and curvy things (soup bowls, eggs, wagon wheels etc), making them straight.

Well, if that isn’t Lee Evans at the O2 I don’t know what is. The heyoka ask difficult questions, and say things others are too afraid to say. Thus, as academics have pointed out, jesters are needed as a safety valve through which communities can give safe expression to their antisocial tendencies: we parody excessive seriousness and deflate pomposity. (Incidentally, the last British nobles to keep jesters were the Queen Mother’s family, the Bowes-Lyons.)

Given this hallowed role of the comedian, I formerly believed that if we ceased to be truly disinterested then we wouldn’t be able to fulfil the important task history has ascribed to us. However, I think things have got into such a state now that I am planning to reverse my position. As of today I intend to become a member of the Labour party, then once the postal order has cleared I am immediately going to resign my membership and after that I will write an article in the Guardian giving my ill-thought-out and incoherent reasons for doing so.

These will be:

1. Spiders. I don’t like spiders and I just feel somehow that Jeremy Corbyn is in league with a secret cabal of giant Spanish-speaking spiders, I don’t know why.

2. Demise of New Labour. I had a load of great standup material about New Labour that I can’t use any more. If any of you saw my highly successful show in 2013, when I returned to the microphone after 17 years, you will probably have noticed that a lot of the best bits were about New Labour including a fantastic routine all about meeting Ed Miliband on The Andrew Marr Show and him telling me that one of his favourite tunes was my 1984 hit record “Ullo John! Gotta New Motor?”.

But I can’t do any of it any more and that’s a real loss. There was something wonderfully venal and self-serving about the Labour party under Blair, Brown and Miliband that made for great comedy and, sadly, all that seems irrelevant now. Honestly, if Corbyn is going to reform the party in his own image – ascetic, socialist, kindly and ethical – then my next act is going to have to largely be about sandwiches. Nobody wants to see that.

Facebook Twitter Pinterest In league with the spiders … Jeremy Corbyn. Photograph: Geovien So/Barcroft Media

3. The Arab World. As, frankly, something of a Middle East bore, the sort of chap who knows his Hamas from his Hezbollah, it has given me great pleasure over the years to see how all western governments have mismanaged their relationships with the Arab world. The philosopher George Santayana (before he formed his Latino-influenced guitar band) once wrote: ”Those who forget the lessons of history are condemned to repeat them.” The western powers seem to have adopted that as a game plan. This blind stupidity has meant I can go on at parties about things such as how Iraq will never be calm until an accommodation is reached between the Shia regime in Baghdad and the “Sunni triangle” (I don’t get invited to parties much any more). Though he was knocked back over Syria, there seems to me to be an alarming lucidity about Corbyn’s attitude towards the region which I don’t like.

4. Disrespect for columnists. While his opponents within the Labour party run around like spooked lemmings every time some journalist says something critical about Corbyn’s policies, Jeremy himself seems unaffected by the bile poured on him by newspaper and magazine columnists. I was somebody who from an early age didn’t believe anything anybody said ever but for some reason in the 1970s and 1980s, long before I began writing for newspapers myself, I began to have an inordinate amount of respect for columns and columnists. The journalists who wrote these opinion pieces in newspapers and magazines always seemed to speak with such certainty that I would find myself getting swept up by their conviction. One would thunder, “Israel is on the brink of making peace with the Palestinians”, and I would think, “Oh that’s nice, my Palestinian friends will be able to go home soon.” Then another would declaim, “Israel is not interested in peace ever”, and I would think, “Oh dear, my Palestinian friends are never going to get home.” I was also strongly influenced by critics who wrote things such as “this album marks a stonking return to form by Bruce Springsteen.” Which was how in the 90s I came to own so many terrible Springsteen albums. Once I too began writing for newspapers, I discovered the intoxicating power completely free from any form of responsibility that comes with having a column. You would write something in the paper and the next day a frightened government would bring it into being – compulsory crash helmets for cats and free hummus on the NHS are just two of the things my columns has produced. These days the power of the print media is reduced, but that did not stop Miliband and his associates being terrorised by critical words from almost any columnist, while, clearly, Corbyn’s people have decided to pay them no attention. Now I personally don’t think much of the opinions of any of these people, but if we allow their views to be ignored then we are one step closer to anarchy.

5. Fear of success. Some of those of us on the left, rather than a fear of failure, have always possessed a much greater fear of success.

I am particularly keen on ideological purity, and am reluctant to see my ideas tested by exposure to the real world. Now, however (even though all the massive forces of the right, the manufactured outrage, the lies in the press, the reactionary bias of the political correspondents on TV have been focused on destroying the “New Politics”), there is an outside chance that a socialist Labour party might attain some kind of power.

I do not wish to see this or any of the other things I’ve mentioned happen, so I will do what many other middle-class media people have done: write an anguished article about why with an almost unbearable pain in my heart I am leaving the Labour party. I just have to join it first.

• Thatcher Stole My Trousers, the second volume of Alexei Sayle’s memoirs, is published by Bloomsbury.