Kenwood: dubb owld boot.

Why did John get rid o' the boot? This pic probably gives the answer: not being designed to withstand the vicissitudes of a British winter, the thing was beginning to fall apart. But here the boot sits, shortly before getting it, down at the bottom of the garden.

Whatevah, great photo. A doff o' the cap to updownsmilefrown for finding this.

Kenwood: pre-sunroom shiznit.

Early 1965, and 3 photos featuring an anonymous Kenwood related person; John's renovations remain incomplete, to the extent that what turned out to be the most famous room in the house hasn't even been built yet.
The first, above, shows the door to the laundry, outside of which squat Julian plus said anonymous Kenwood related person, to the right of which would soon see the sunroom.
Compare with the view a couple o' years later:

John and Yoko would also be "photoed" on these very steps in December 1968:

Second, and moving on to the boot: at last, an exact location - half-way up the front drive, a fact confirmed by Dot Jarlett's e-book (of which, more anon):

Frontage and, moreover, etc:

Finally, and thank etc., a spot o' carpet beating outside the living room:

More thanks to Mr L.

Kenwood: the boot gets the boot.

So, what became of the boot? Local magazine Surrey Life has uncovered the answer. It turns out the boot was at Kenwood for no time at all.
To be brief, John quickly grew tired of it, and so it was donated to the local Rag Week (an annual event where British students raise money for charity, often by being irritating). In this case, the boot was hollowed out, put on wheels, and pushed to Luton in a sponsored event. What became of it thereafter I don't know, but it probably didn't survive. A fitting end, somehow.

Kenwood: boot up.

Escaping the attic...Glenn Marteney has sent in a much bigger and better quality (click on it) scan of John with his outsize boot. This boot, originally a Help prop, was said to be placed at the bottom of the garden , in the section overlooked by the sunroom end (indicated on the aerial pic above). Pure (and particularly idle) speculation on my part, but are those trees you can see in the boot pic the same as the ones circled on the aerial shot? Possibly...not. And what became of the boot? Thanks, in any case, to Glenn.