 The Chief Mechanical Engineer, H. J. Bennett, wrote to the CME of the New Zealand Government Railways, P. R. Angus, requesting a book of engineering drawings of NZR locomotives, and also asking if the NZR had any locomotives it could sell to TGR, enquiring in particular to the WW class 4-6-4T tank locomotives.Angus advised Bennett that the NZR could not spare any WW class locomotives as they were indispensable to NZR.He instead offered the WF class 2-6-4T as a suitable design that could be released due to the conversion of locomotives of classes BB (4-8-0) and C (2-6-2) to heavy shunting locomotives.