Clive D. W. Feather wrote:

John Shelley writes
Trains on the two main routes from Moorgate would have coupled at
Highgate.
ITYM "connected". Attempts at coupling would have been interesting,
to say the least.
No, coupled. Just like on the big railway.
I think Bill is pointing out that the vertical difference between the two
lines at Highgate make that a bit of a problem.

In which case, both you and Bill are misunderstanding.

Train departs Moorgate, runs via Drayton Park, Finsbury Park (high
level), to Highgate High Level. Splits.
* One part turns right at Park Junction and heads to Ally Pally.
* The other part goes straight ahead and continues to East Finchley (or,
in the peaks, High Barnet).
Reverse the process for southbound trains.

I said "two routes *from* Moorgate".

Sorry to be so pedantic, but wouldn't those have *un*coupled at Highgate?