The cruiser Ajax, the eighth Royal Naval ship to bear the name, was one of the Leander class of 6" gun cruisers and was built by Vickers-Armstrong at Barrow and launched on1st March 1934. Early in the second world war the Ajax, her sister ship the Achilles of The Royal New Zealand Navy and the Exeter took part in the remarkable action at the Battle of The River Plate. The German pocket battleship Admiral Graf Spee, a commerce raider which had already sunk several British merchant ships was intercepted at dawn on 13th December 1939, by the three cruisers commanded by Commodore later (Admiral Sir) H.H. Harwood. The Graf Spee immediately opened fire at a range of nearly ten miles and the three cruisers replied and although completely outgunned closed the range. A Seafox from Ajax was catapulted off and this single aircraft spotted the gunfire for the whole engagement, the Exeter's aircraft both being damaged before they could be launched. In the ensuing battle the Exeter was badly damaged and forced to fall out of the action. Two of the Ajax's turrets were disabled but the pursuit was maintained despite smoke screens and evasive manoeuvres and many hits were scored on the Graf Spee. Shortly after midnight the pocket battleship sought refuge in the neutral harbour of Montevideo. Ajax and Achilles, together with the Cumberland which had arrived from the Falkland Islands lay off the river mouth to wait the Graf Spee. On the evening of the 17th December the Admiral Graf Spee weighed anchor but while still in territorial waters the crew were taken off and the Graf Spee blew herself up. The Ajax survived the war which she spent almost entirely with the Mediterranean fleet, being refitted in the U.S.A. in 1943 and was scrapped at Newport in 1948. Her sister ship the Achilles (basically identical) also survived the war and was transferred in 1938 to the Indian Navy and renamed the Delhi. H.M.S. Ajax had a length of 555ft., a beam of 55ft. and a draught of 16ft,, displacement was 6,985 tons.
Her armament consisted of eight 6 inch guns, eight 4 inch A.A. guns and a variety of smaller anti-aircraft weapons. She originally carried two aircraft and her complement was 550. The geared turbines of 72,000 S.H.P. gave a speed of 32.5 knots.