Gauge discussion makes me always wonder how the British railways would have looked like if the Brunel gauge became the dominant gauge
Probably about the same but quite a bit more expensive. The 1435mm gauge allows both very high speeds and very heavy loads (not necessarily on the same track), which are ultimately constrained by other factors. A broader gauge would increase the size and cost of track and running gear, and limit minimum curve radii, without delivering any benefit. With hindsight we are pretty lucky that the width of a Tyneside coal wagon turned out to be about right for so many other purposes.
The mind goes to an interest-arousing newspaper comment piece -- maybe in the
Guardian -- some years ago now; seemingly by some "journalistic clever-dick", not a scholar of railways as such (a while back, I started a thread re same, on "Speculative Discussion" --
Slightly odd thoughts re the 7 ft. gauge, OP 23/ 10 / 18). This chap's theme was that 7 ft.'s being the dominant gauge in Britain: would have been a good thing, since a rail system on that gauge would have been mostly a main-line one only. This: because a gauge that broad, would have been ill-suited to tortuously-wandering rural lines -- few of which would, thus, have been built. That would have been a good thing, because such lines were from the first, of doubtful point or benefit -- money-losers, which would in any case have been, before many decades were out, superseded and made irrelevant by the rise of road motor transport.
The overall general feeling in the thread; was that although there was something (not a great deal) to the guy's thesis about 7 ft. gauge's unsuitability for sharply-curved-and-steeply-graded rural routes: even if that had been a factor of much significance -- in the mid / late 19th-century climate of enthusiastic railway development, Britain's rail system would have turned out as dense as in "our real-life time-line", or more so (different no doubt, in routeing details). There would have just come to be, to the 7 ft. trunk-line network, a great number of feeder lines of gauge(s) of less breadth -- inaugurated by the main-line companies and / or private undertakings. (Break-of-gauge problems would have been seen as "there to be dealt with".) Humans are conspicuously
not cautious or far-sighted: our way of functioning greatly tends to be, "go full-steam-ahead on what seems a good idea at the time; if it later proves less so -- it can be adjusted, or may adjust itself".