24 Chapel Street: internal layout.

As the old (and moving) trad. arr. has it: "Chapel Street, Chapel Street, Hard to walk to, Without any feet" (What is this drivel? - Podiatry Ed.). Number 24 was, o' course, Brian's final abode, a place of psychedelic high-jinks and not a little angst, as the repercussions of Brian's increasingly chaotic private life played themselves out. The plans here date from the late 1950s, and the eagle of eye will spot certain discrepancies (eg there are now 3 windows on the side wall, but only 2 at the time of the plan for the upper floors).
Nevertheless, this is more or less the layout as Brian would have known it. But enuff o' my yakkin'; for the BBC Arena documentary on his life, former PA Joanne Petersen drove back to Chapel Street and ran through the place (not literally) as she remembered it:

JP: "Downstairs was the staff quarters; this was where his housekeeper and her husband lived." ( ie Spanish couple Maria and Antonio, of whom little is so far known):

Joanne had nothing to say about the ground floor, but a small part of the hall (or vestibule thereof) could be glimpsed behind Ver Fabs on the night of the Pepper launch party. Note too the kitchen to the rear, from where Joanne phoned Kingsley Hill on the weekend of Brian's death to express her concerns to Peter Brown:

JP again: "You went upstairs to the sitting room, and behind the sitting room was Brian's study where he worked.":

So the area marked "Boudoir" on the plan was Brian's office, which explains why it is dark in the party photos:

JP: "The second floor was his suite... you went in through the double doors to his dressing room, and then into his bedroom and then through there into his bathroom. His bathroom was pretty unique. It was totally white... with a huge (photo of) El Cordobes all on one wall, it was very imposing."
El Cordobes was, as ye will doubtless know, a Spanish bullfighter who Brian had a "thang" about.  From the description, it's possible that the door to the bathroom on the plan here was blocked off, and another put in beside the chimney area in Bedroom 1. Said Bedroom 1 was, o' course, the place where, tragically, on 27th August 1967, Brian accepted a teaching post in Australia:

JP: "The rest of the top floor was two rooms knocked into one, and that was where I worked in one corner. It was the office by day and the playroom by night. It was where he had all his memorabilia, and the present that Elvis's Col. Tom Parker had given him. It was just full of treasures of Brian's. It was also where everybody went up at night to play, and at the weekend I used to put my typewriter under my desk because then it wasn't lost anymore."
Presumably the "two rooms knocked into one" were Bedrooms 4 and 5:

And there we have it. I haven't found any record of planning permission post-Brian, so presumably the house remains more or less the same. One day, no doubt, it will come on the market again, at which point we shall see.
Many thanks to Julian Carr for digging up (not literally) the plans, and grateful acknowledgement to James Boyles for taking the Chapel Street pic.