Earl Purple wrote:

You'll probably find, if you look at a map, that although the journey
towards Cockfosters is called "Eastbound",

Unless they've changed them recently, all of the Cockfosters-bound platforms
from Holborn to Oakwood are marked "Northbound".

the East-most station is Manor House after which your journey heads back
towards to the West
(as well as North).

.... although Southgate is east of both of its neighbours.

The thing that's always surprised me is the way the Metropolitan Line
pretends to be a north-south line, at least between Baker Street and the
sticks.