Leiper was an Irishman who worked as an iron turner. By 1920 he was unemployed and a widower, and devoting himself to his work as Organiser of the Clydebank Housing Association. He set up an office in his single-end tenement home in Stewart Street in Dalmuir, where he created a library of material relating to rent legislation and plotted a series of guerrilla legal campaigns against rent increases in the Burgh.
Leiper was active as a "moderate" in the Dalmuir branch of the Amalgamated Society of Engineers, but he insisted that the CHA should not align itself with any one party - a view that brought him into conflict with the ILP-leaning Scottish Labour Housing association and apparently led to the CHA's disaffiliation from the latter organisation. He was suspicious of the motives of the ILP in its initial support for rent strikes in the West of Scotland and opposed calls from David Kirkwood and other ILP-ers in 1920 to pay no rent, insisting that the CHA would support only those tenants who paid the 1914 rent. Indeed, Leiper was contemptuous of what he called "Socialist Softies and Fat Heads" in Government and on the local Council, when their support for the rent strike subsequently wavered. As the Labour group on the Town Council did not support the CHA's policies on rent control, he fought and won the local election for a seat on the Council, standing as an Independent in the 4th ward.
The Irish Land League, which had campaigned for fair rents and fought court actions to obstruct landlords' attempts to increase rents, was apparently Leiper's greatest inspiration . He made it clear in the letters to the local newspaper that he saw the Rent Strike as a battle in the campaign to win "fair rents" for working class tenants, and "the provision of houses for the working classes on an interest-free basis". With the Dumbarton lawyer David D Cormack he uncovered numerous loopholes in the law. Together, they frustrated Clydebank factors and property owners by successfully challenging rent increases on the grounds of improper notices and other failures to follow proper, but often complicated, legal procedures relating to the notification of increases in rent.
Thousands of Bankies, of all political persuasions, supported the campaigns of the CHA. Leiper, Cormack and other Association leaders were prepared to represent in court any Clydebank tenant who refused to pay more than the pre-war rent. Leiper worked tirelessly to carry the fight to the landlords, earning himself nicknames such as the "Gownless Lawyer" and the "Tenants' KC". The rent strike remained firm in Clydebank long after it had begun to peter out in other areas, largely because of the string of successful court actions mounted by Leiper and his team, challenging the legality of notices of increase and other legal documents and procedures. However, the campaign was doomed to failure without the support of politicians in the Town Council and at Westminster, and the loopholes in the rent laws were closed, one by one, during the mid-1920s.
On 21 July 1927, Leiper was badly injured when he stepped in front of a motor car on Dumbarton Road. He died shortly afterwards, and the Clydebank Rent Strike, already weakening, did not outlive him for long. Leiper was a courageous and successful leader who worked tirelessly for what he regarded as the best interests of the community. He is surely one of the most important yet enigmatic figures in the history of the Burgh.