Historical Specifics:

The 5.5 inch medium gun was introduced into British service in 1942 and three pilot guns sent to Australia for possible local production. Ultimately Australia decided to purchase the guns from Britain and an order for 72 guns was placed. By mid 1944 27 were delivered but the final purchase numbered only 40 guns. They did not see operational service with the Australian forces. They were finally withdrawn from service in the mid 1980s.