it comes from an old routine by Alexei Sayle alleging that leftwingers would knit their own yoghurt. I think he did it in one of the Secret Polcemean's Ball films.
'Yoghurt knitters', it usually means people from the far left who are bureaucratic, whinging, very PC, protestors who are offended by anyone who doesn't share their view on the environment, war, society etc. The term refers to the uselessness of trying to knit yoghurt.
So the Geezer has been stealing his material from a Left Wing comedian all this time. How ironic. I assumed it was a Littlejohnism or other mail scribe.
its a very very old gag and only ever really gets aired here on answerbank anymore I believe - its quite irritating... though not on the same scale as people saying "noo labour", that just makes me what to scream IT WASN'T FUNNY TEN YEARS AGO!!!!!!!!
Ah, so that's it. The invention of an erstwhile communist. Not an original thought, after all.And RIG is known for original thought, which makes his use of it astonishing.