In terms of £££, what budget was available to the GSR during that period for building new locomotives?
What were the building costs of 800-802, and 850? How much money was left after that?
Note 850 was made possible partly because it made use of some existing Woolwich Mogul parts.
The impression I get is that, money being somewhat scarce, the GSR stuck to the conventional principles that it saw as being cost-effective, or cheap. If the 25 engines of the 342/670/700/710 had not been built, what could the GSR have created for the money not spent?
Innovation tends to cost, so developing a new mixed-traffic design, with Walschaerts outside motion, may not have resulted in as many as 20 engines. There would have had to have been some sort of testing of the initial tank and tender designs to see if they really were of universal use, before asking for approval to build more.
In the case of the 2-6-0, would all-new tenders have been built for them, or salvaged from older withdrawn engines? We don't know.
I'm also looking at the W class moguls in the North which were introduced in 1933:
- As a contemporary design, what did they cost the LMS(NCC) to build?
- Would they have been suitable for use on the GSR network and, if so, on which routes?
- Would it have been realistic for the GSR to ask permission to test a W or two? If such permission was forthcoming and the engine found suitable, would the LMS have then agreed to build them for the GSR? What would that have cost?