In message , Chris Henderson
writes

When British Rail was created, what were the reasons for not making the
London Underground part of it?

I should think that one of the reasons was that it would have meant
splitting control of the underground service from the bus, coach, tram
and trolleybus network.

Doesn't the existence of two very separate railway networks in London make
travelling in or across London harder (when separate fares and/or tickets
are needed),

I think there's more integration than you imply - I almost always use a
travelcard in the capital, which is valid on tube, NR, buses, etc. - and
there's not really much duplication of staff between the systems.

Historically, the first level of integration was always between
underground and road forms of transport - that long pre-dates the 1948
nationalisation.

But there is certainly a need for better integration of NR into the rest
of London's transport system and there do at last seem to be some moves
in that direction. But there will always be compromises, since NR serves
an awful lot more than just London.

--
Paul Terry