On Jun 14, 8:18*am, Mr Thant
wrote:

It looks like the yellow shape that makes up the Zone 3 border has
been inadevertently nudged to the left. Wembley Park has the border
passing straight through it, but is not marked as a boundary station,
whereas it misses the boundary stations in East London.

Perhaps it's because of the slightly messy compromise they've come up
with to show that Heathrow Connect and Heathrow Express are 'outside'
the zonal system, whilst the Piccadilly line isn't - despite them
obviously meeting at the Heathrow stations! They've tried to draw the
Zone 6 boundary in between the two lines, but had to add one of those
explanatory boxes anyway...