...in your last paragraph, my take on Brunel much to Mike's vehement disagreement, I know.

His engineering was pretty much flawless, but the practical application was almost invariably flawed.

Broad-gauge had an unanticipated problem with curvature and rolling resistance in curves, simply due to the solid axle. Simplistically, you need a larger radius of curvature for a broader gauge to achieve the same level of rolling resistance because each wheel travels different distance around a curve for the same rate of rotation. One wheel is always sliding a little bit because there is no differential. Making wheel profiles somewhat cone-shaped helps, but only a bit as the forces aren't really repeatable.

The other unanticipated issue with broad-gauge is the aspect ratio of the vehicles themselves. Where Brunel was convinced lateral stability would be enhanced (and is right) the fore-and-aft stability suffers as the vehicle length remains the same compared to width. The solution is of course to make the vehicle longer to keep that aspect ratio of length to width, but then the bigger heavier result exacerbates the rolling resistance issue in the previous paragraph.

Both of these consequences meant broad-gauge needed more space because of geometry limitations and required more maintenance because of track wear, the former not an advantage in a country where space was at a premium. It isn't around, not just in Britain but worldwide, for sound reasons, and not just standardisation (if Australia is any example. GRIN!)

Then there is that great whacking steamship of his. Very impressive and a source of great national pride, the Great Eastern, but horribly flawed in detail, never made a profit in the Atlantic and too big for the India route. It ended its rather short career as a cable-layer.

No doubt a genius and worthy of his fame. Impressive feats of mechanical and civil engineering but so often either not quite successful or attempts at solving a problem that really didn't exist.