He served for six years as an apprentice fitter-and-turner with R&W Hawthorn Leslie & Co at Newcastle upon Tyne and after passing the necessary examination was admitted to that company's drawing office during his apprenticeship.
The design was similar to the M class supplied by Beyer, Peacock & Co, but the lengthening of the firebox required work to be done on the re-distribution of weight and the pivots.
[2] Despite his insistence that their construction constituted essential war work, production of the S Class was postponed, and it wasn't until 1943 that the first three of an eventual total of ten were placed into service.
The S class was to prove one of the more controversial of Western Australia's locomotives; suffering from a variety of early problems due to Mills' implementation of some bold new ideas.
The problems in Western Australia, however, were exaggerated by a succession of State Governments having provided little for the railways, meaning that they had not yet recovered from the effects of the Great Depression.
[3] Approximately half of the WAGR's locomotive fleet dated back before the turn of the century, and by 1943 a quarter were out of service pending overhaul.
The Australian and American military machines required of the Queensland Railways (QR) a logistical task that they were hard-pressed to accommodate; in fact a worse situation could scarcely be imagined.
When the military forces needed machinery, people, and supplies moved in vast quantities as a matter of priority they had at their disposal the modest infrastructure of QR; light-weight track and structures, a tortuous geographic profile, unpretentious locomotives with low axle-loads, and train lengths limited by these factors.
These gave the Commonwealth full power and authority to control rail and road transport and do all things necessary to give effect to the regulations.
The CLTB was also responsible for the acquisition, by purchase or manufacture, of any required vehicles and accessories and to operate and use them and determine routes and priorities of transport.
His secret report — to a singular Term of Reference — would be used to justify the acquisition of what would become known as the Australian Standard Garratt, to alleviate a wartime motive-power deficit most critically being felt in Queensland.
Once the decision had been made to proceed with the ASG, Ellis elevated Mills to Controller of Locomotive and Rollingstock Construction for the Ministry of Munitions with responsibility for the actual design work.
At a time when the administrators of the QR had lost the legal right to conduct their empire as they pleased, the way in which the Commonwealth officers approached their task was vital if proper organisation was to be achieved.
If a high priority were then obtained and if a co-operative scheme could be established Australia could probably expect to receive three units per week with the first deliveries to be made six months after order.
They did agree though, that their locomotives then being built by Clyde Engineering could be deferred in favour of that company assembling ASGs, and promised staff to carry out inspections of construction.
They were considered by both QR and its enginemen to be deficient in many respects — and later, perhaps even unsafe due to their unflanged leading driving wheels — and met with great resistance.
Mills' intransigence to criticism did not place him in a good light following an eventual Royal Commission into the ASG and also meant that modifications that may have resulted in their successful operation were delayed or refused and the locomotives were finally withdrawn to become monuments to human folly of various categories; but perhaps mostly hubris.
He states of the development and construction of the ASG, "The reality was, despite the QRG's lethargy, whether justifiable or not, there is no excuse for the Commonwealth through the agency of Clapp and Mills, visiting upon the QGR and its military users what stands out as a disaster unprecedented in the history of locomotive engineering in Australia."