I would like to have a go at "the walrus was Paul", even though the
google/group archive of USENET shows 520 people have already posted on
this topic.

Suppose that one day Paul showed up at the studio spouting what
sounded like nonsense to the other Beatles.  Such nonsense had never
been heard in the studio before and it seemed for a moment that Paul
was the walrus:

   `The time has come,' the Walrus said,
       `To talk of many things:
   Of shoes -- and ships -- and sealing-wax --
       Of cabbages -- and kings --
   And why the sea is boiling hot --
       And whether pigs have wings.'
   -Lewis Carroll

Now any good Beatles fan will remember the photograph of John holding
a pig by the ears that came with the Imagine LP.  John was showing
that pigs do not have wings, it is plain to see.

In my imagined scenario, Paul's Walrus-speak was about Martin's subtle
influences on Beatles music and lyrics, much of which can be heard on
the outtakes released on the recent Anthology collections.  Paul may
have been the first to notice that Beatles singles such as "Ticket to
Ride" and "We Can Work It Out" were breakup kinds of love songs that
were very different from Beatles love songs up to that time.  These
songs may have been about US/UK relations during the early days of the
Vietnam war, and Paul was first to notice.

I suspect, without any really provable arguments, that Paul's
Walrus-speak had to do with George Martin's wartime connections.  I
suppose that Martin might have done sonar work in the war, similar to
the Jones character in the movie "Hunt for Red October", and that is
how Martin became a recording engineer after the war.  In short,
Martin 'lived in a hole in the ocean' and was trying to influence
Beatles lyrics 'to make a dovetail joint' in US/UK relations.

Paperback Writer came out about the same time as the Warren Commission
report.  It is interesting that Warren Commission member and former
President Gerald Ford's son worked at the Detroit Free Press at that
time.  This is close to "his son is working for the Daily Mail"  Let
me add that I think President Ford was one of the best Presidents we
have had. But I believe so strongly that "Day in the Life" is about
the day after the JFK assassination that I won't even discuss it.

Maybe it really was a British Invasion, with the morale operations
groups working through Mr. Martin without the knowledge of the
Beatles.  This seems to apply only to the songs released as singles. 
When they figured it out the Beatles turned in their MBEs and had
Sergeant Pepper bury the Beatles.  Beatles was all an act anyway.

Also, in 2001 the British Public Record Office declassified 8
documents that show that a Wilfred Macartney was a 1928 era Russian
spy.  Perhaps Wilfred is Paul's 'very clean' grandfather.
http://catalogue.pro.gov.uk/BasicSearch.asp

I think that the Beatles soon began giving _all_ of their best songs
to other artists, such as "Ball of Confusion"  and "Just One Victory" 
Whatever the truth is, Pink Floyd later proved that pigs really do
have wings.  And the British Government was certainly right about our
actions in Vietnam.  But I would like to know the truth, and "I curse
the gloom that is upon us"

If you believe very much of my imaginings, then YOU are now the walrus
too.