Why was the Walrus Paul'?

In his Playboy interview (1980) Lennon tried to explain the lyrics of 'I am the Walrus" 

“Walrus is just saying a dream,”. That dream is from the world of Through the Looking Glass, albeit updated to include the sound of a police siren and images from an acid trip 

Perhaps unwisely Lennon let further daylight in on the magic..

“You know, you just stick a few images together, thread them together, and you call it poetry. Well, maybe it is poetry. But I was just using the mind that wrote In His Own Write to write that song.” 

He also admitted that he had had 'no idea' who or what was the 'eggman'.

So how does Paul fit in?

 In his 1971 Rolling Stone interview, tried to explain the McCartney reference in Glass Onion: 

Here's another clue for you all. The Walrus was Paul. 

He was aware, however, that all 

But it doesn't sound very affectionate.

Interestingly, Glass Onion was a genuine collaboration between John and Paul. The theme (an attack on the 'pseuds' over-interpreting Beatles' lyrics) sounds typical of Lennon but in fact came from McCartney.

Their relationship was fraying but here they come together in a howl of complaint about how Beatles' lyrics were avidly scoured for hidden messages.  

Ian Macdonald  suggests that the 'sour A minor melody' and snarling tone of the song express the intent of they lyric" - a  sullen two-fingered gesture fans in general as much as  conspiracy theorists ('you all').

According to  Macdonald 'Glass Onion' says less about the credulity of pop fans than the self-regard of pop stars.'

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