The primary generator was a fully sealed ultra-high-pressure circuit working between 1,400–1,800 psi (9.65–12.41 MPa), filled with distilled water that transferred heat from the firebox to the high-pressure drum.

Approaching Carstairs station at slow speed, one of the ultra-high-pressure tubes burst and the escaping steam ejected the coal fire through the fire-hole door, killing Lewis Schofield of the Superheater Company.

[8] The boiler was eventually repaired and Fury moved to Derby where a number of running trials were carried out until early 1934, mostly revealing significant shortcomings in performance.

Although tolerating the trials from Derby, Stanier didn't devote much effort to rectifying the faults Fury displayed, no doubt because of his many other work pressures and development of the LMS Turbomotive.

Fuel is only one part of the operating costs of a steam locomotive—maintenance is very significant, and introducing extra complications always increased this disproportionally.

The failure was investigated, and it was concluded from both incidents that inadequate water circulation in the ultra high pressure circuit was responsible.