Mark Brader:
The deep-level lines ... marketed themselves as being a New And
Improved kind of underground railway ...

In due course the older lines electrified and got rid of their steam
locomotives,

Clive Feather:
This implies that it was after the tubes were built.

It was done after enough of them were built for it to be clear what
people preferred.

In fact, the key parts of electrification of the subsurface lines were
done in 1905-6. At this point the Central, part of the Northern, and the
Waterloo & City were open

And most recently, the line from Moorgate to Finsbury Park that is no
longer part of the Underground.

and the Bakerloo was about to open. The Piccadilly and the Charing
Cross branch of the Northern were still under construction.

Yes, exactly.
--
Mark Brader "Doing the wrong thing is worse than doing nothing."
Toronto "Doing *anything* is worse than doing nothing!"
-- Lynn & Jay: YES, PRIME MINISTER

My text in this article is in the public domain.