On 20th August 1957, Job No. 5794 was issued for the installation of Smith-Stone speed recording equipment on all the ex-LMS 4-6-2s 'in view of the increased number of high-speed trains now operating in this (London Midland) Region'. The work was carried out at Crewe and engines were called in specially to be fitted. The Smith-Stone ones were driven by a return crank on the rear left-hand crankpin. The generator was mounted on the end of the crank and steadied by the armoured cable that curved up to the wheel size adjustment rheostat box clipped to the platform.