I don't know how long ago it seems to you, but the truth is this: Lee and Herring stopped being a full-time comedy double act in 1999. They get together for the odd reunion gig once in a while, but happily admit their time has passed. As Stewart Lee says, their double act "was predicated on the conflict between a thin man and a fat man... there is no mileage from the conflict of two similarly overweight men."
It's nice that Lee's come to terms with achieving the same BMI as Richard Herring, but to be fair they were never just a fatty and thinny duo. And the key differences in their personalities come through in the two very different books they published this summer, even though both of them start with the word 'How' and document a period of their lives in the early 21st century which saw them both shacking up with female stand-up comics.