Aug 31, 2019 United Kingdom (1958) Self-Propelled Gun – 234 Built. In the late 1950s, the United Kingdom was looking for a new Self-Propelled Gun (SPG). It was envisioned that this would replace the Ram-based Sexton, a Second World War-era 25-Pounder gun-armed SPG that was still in service with the Royal Artillery.It was also planned that it would somewhat replace the 25-Pounder gun in general