of RSSILA, but he continued to be a fierce advocate for returned soldiers. On 30 October 1925, Blackburn was transferred as a lieutenant from the Reserve of Officers List to the part-time 43rd Battalion of the CMF. In the same year, along with McCann, he formed the legal firm Blackburn and McCann, continuing the association they had during the fighting at Pozières. On 21 February 1927, Blackburn was promoted to captain, still serving with the 43rd Battalion. In early 1928, Blackburn became a foundation member of the Legacy Club of Adelaide, established to assist the dependents of deceased ex-servicemen; he later became its second president. In this role, he created a Junior Legacy Club for teenage sons of men who had died, which conducted activities such as camps and sports. Blackburn was transferred from the 43rd Battalion to the 23rd Light Horse Regiment on 1 July 1928. In September and October 1928, Blackburn helped raise a volunteer force which was used to protect non-union labour in an industrial dispute on the wharves at Port Adelaide and Outer Harbor. Initially called the "Essential Services Maintenance Volunteers" (ESMV) then the "Citizen's Defence Brigade", the men of this organisation, armed with government-issued rifles and bayonets, were deployed by the South Australia Police to intervene in the dispute between union and non-union labour on the docks. There was no fighting between the force and the strikers, and the dispute was resolved by early October. Following the amalgamation of light horse regiments, Blackburn was transferred to the 18th/23rd Light Horse Regiment on 1 July 1930, and to the 18th Light Horse (Machine Gun) Regiment on 1 October of the same year. In 1933, Blackburn became the coroner of the city of Adelaide, a position he held for fourteen years, with leave of absence during his World War II service. In this role, he was criticised for refusing to offer public explanations for his decisions not to hold inquests; it was criticism he ignored. The ALP attacked Blackburn's decision-making as coroner, according to Faulkner, this was probably influenced by his involvement with the ESMV in 1928 and his alignment with conservative politics. They were joined by the editor of The News, who ran several editorials criticising Blackburn. In his role, Blackburn often dealt with deaths of returned soldiers, and murders committed by them. On 6 May 1935, Blackburn was awarded the King George V Silver Jubilee