London's loyalties

ROUTE 1 post No. 1966 seems an appropriate occasion to return to the topic of ENGLISH FOOTBALL.
Back in March, I wrote about a scarf illustration in the book "The Soccer Tribe" that mapped club loyalties in LONDON.
I wondered how club-support boundaries might have changed in the (now 30) years since the book's publication.
Reader RogField, apparently a Tottenham Hotspur supporter, recently alerted us to an updated version of the club loyalties map.
The map lists boroughs and denotes football club grounds. With coloured coding it also shows the spread of a club's loyalty over the capital.
I was interested to see the spread of Chelsea supporters on both sides of the River Thames, the clearly delineated enclaves of Queens Park Rangers and neighbours Brentford and Fulham and the blurred borders between Spurs and Arsenal in north London.
The amount of Arsenal support south of the Thames was also a surprise to me -- and probably provides a source of much disappointment for the people attempting to sell tickets to Crystal Palace, Millwall and Charlton home matches.
The mapmakers credit "The Soccer Tribe" for inspiration and also offer the caveat that this new map remains a work in progress.
How will loyalties look on the next map?