This locomotive was built by Andrew Barclay in 1918 to fulfil an order from Sulphide Corporation of London but it was requisitioned on completion by the Ministry of Munitions and sent to Persia where it remained for many years, latterly in the service of the Anglo-Persian Oil Company.
It is uncertain exactly when Ajax returned to the UK but it was recorded as working at Llandarcy Refinery, near Swansea, and later at the Stanton Iron Works, Sheffield. It finished its industrial service at Harlaxton Ironstone Quarries, near Grantham, being withdrawn in 1968.
The locomotive was purchased by Henry Frampton-Jones who placed it on loan to the Isle of Wight Steam Railway in 1972. No major restoration work was carried out for over twenty years but, following agreement regarding its future use,a full overhaul was completed.
The majority of the work required was undertaken by the works staff at Havenstreet and, in January 2002, the boiler was dispatched to South Wales for contract repair. This included the fabrication and fitting of a new, all steel, inner firebox. The boiler was steam tested at Havenstreet in December 2003.
Following this successful test the superstructure was extensively rebuilt and a series of test steamings commenced in October 2004. Ajax hauled its first public passenger train during the summer of 2005 and was in service until the end of the 2014 timetable, when it was withdrawn for overhaul.
The locomotive remains based on the Isle of Wight Steam Railway where in 2020 it was on static display.