Looking at Victoria in Australia most of the Melbourne area had over head wires by the 1920's ish
Melbourne to Traralgon main line was completed in 1954.
I think I am correct in saying U.K. main line electrifcation started in the mid 1970's
Should/could the U.K. have jumped from steam to over heads earlier?
Or was it a case of cost fuel being cheaper/political reasons?
The answer depends on how early "early" is, I think. In "Outlines of Electrical Engineering" by Harold H Simmons* (Cassel, 1909), there is Section on electric traction, with three short chapters on trams and one on railways. He considers the economics of electric versus steam and (for trams) cable traction - but I can't see any mention of internal combustion, which seems odd (with hindsight, at least).
He concludes that electricity wins for trams, with the exception of very steep hills. Overhead feeding beats ground-level in streets, and always has done. For railways he finds the economics are not yet clearly in favour of electricity, but other factors (safety, smoke-free tunnels, and laws dictating the choice) often swing the choice in urban and some suburban systems.
For both trams and (sub)urban trains he sees the state of the art as mature - meaning good enough, not that it won't evolve incrementally. They use around 500-600 V
DC▸ , with an upper limit of 1200 V imposed by the commutators. AC motors were never used, since they had so little torque when starting and needing to accelerate.
Main lines, even then, were not suitable for third rail - a unanimous view, except in
BR▸ Southern Region down to quite recent times! While the Swiss had tried using AC motors, with a three-phase supply, this was a demonstration (in the Simplon Tunnel) and never found more general application. AC supply was being used, but with DC motors (which change direction by having the leads of their field coils swapped over). The commutators (again) and the inductance of the motors together meant that 50 Hz could not be used, but 25 Hz AC was already being used instead.
So while
OLE▸ was established, there was no clear way forward as to what flavour. With DC, voltages had to be too low to be efficient; while for AC, at 25 Hz the motors and transformers were big and performance not that great either. I think (though he doesn't say as much) he was not foreseeing big generators in public supplies, or a grid, but smaller steam power stations run by the railway. So steam locomotives still had a cost advantage against all that infrastructure and losses.
Again, it was external factors that pushed a few railways towards electric traction. Abundant hydro power, a shortage of coal, or long tunnels (all true for the Swiss, especially) are mentioned, plus imposed legal requirements again. He mentions the Midland Railway's line from Lancaster to Morecambe, but mainly as an example of the "Siemens" compound catenary (three wires). His main example is the New York, New Haven, and Hartford Railway, where the lines near New York City were forbidden to use steam. In various places they used third rail (bottom contact), an overhead rail (presumably also DC), and 11 kV overhead. The OLE was an odd system with two catenary wires side by side and V-shaped droppers to the contact wire - which seems now to be solving a non-problem.
*The full text (and some of the pictures) of Simmons was digitised by Google Books, but for some reason is only
available from the Internet Archive - p787 (p832 on line) for the section on electric traction, and p815 (p860) for railways.