It was noted that the tractive effort of the new engine was 10,260lbs, considerably less than the 12,890lbs of the slightly smaller NZR W class 2-6-2T, and that a new boiler with a greater working pressure of 140psi would be required to have made the conversion of any real use.

It was considered uneconomic to fit new boilers to the old V class frames and running gear, which would have retained the obsolete Stephenson link motion and so the proposal lapsed in favour of developing the last three engines of the WA class 2-6-2T tank locomotives, nos.

With a maximum 9.3 tons axle loading on the driving wheels, the new locomotive would have a wide radius of action.

By the time of the final Picton transfer in 1936 there were six engines - the seventh, WF 398, had been returned to the North Island three years previously in 1933.

From 1935 onwards, two engines of this class, WF's 398 and 400, were converted to one-man operation by lowering the coal bunker and fitting one continuous back window to the cab, and allocated to work the Greytown Branch.

[3] Both locomotives were withdrawn on closure of the Greytown Branch; WF 400 in December 1955, while WF 398 remained in service for several months primarily to run the demolition trains and during which time it moved the Greytown station building to Woodside Junction to become the new goods shed there.

In 1909, trials were conducted with WF 436 to see if a solution could be found to reducing the amount of smoke produced by engines passing through the Lyttelton Tunnel.

Eventually, the problem was solved by the electrification of the line between Christchurch and Lyttelton in 1929 when the EC class entered service.

[6] In 1955, Addington Workshops fitter Noel Mather was sent to Nelson due to the failure of all four WF class locomotives.

WF 404, previously the only operable steam locomotive at Nelson, had been removed from service with small cracks in the smokebox saddle.

The remainder of the brake piping remained in case there was ever need to re-equip these locomotives to run with air-braked trains.

Immediately following the Great Depression in 1936, the Tasmanian Government Railways (TGR) found itself unable to manage the increased tonnages it was being made to handle.

The WF class was by now largely confined to shunting work, except for those allocated to the isolated Picton and Nelson sections.

Accordingly, Angus wrote to the District Mechanical Engineers in Wellington and Christchurch, before asking James Binstead, the DME for the South Island, to select four WF class locomotives for sale.

On receipt of this request, locomotives WF's 381, 385, 436 and 437 were withdrawn and transferred to Hillside Workshops for overhaul and rebuilding to TGR specifications.

Certain engines also suffered from reliability concerns, which later led to trial modifications made to DS 7 (WF 434) by shortening the smokebox by 520mm and fitting a narrower 'Master Mechanics' funnel.

The first four locomotives were identifiable from the later four by several distinguishing features: The locomotives were all fitted with three-link screw couplings, vacuum brakes in place of Westinghouse air brakes, Detroit sight-feed lubricators, and electric marker lights on the smokebox side and bunker to make them suitable for TGR service.

The locomotives were used mostly between Regatta Point-Dubbil Barril and Rinadeena-Queenstown, and had their cowcatchers removed to facilitate transfer over the rack section of the line.