His cousin, Arthur Otley, served as general secretary of the National Association of Operative Plasterers (NAOP), which Thomas joined in 1890.
After only three months, Thomas Otley replaced Lamb in the role, and worked closely with Deller.
[1] Deller died in January 1906, and Otley was appointed as acting general secretary.
[1] From 1910, membership began increasing again, the Cork City Society of Plasterers joining the union, and the National Health Insurance Act 1911 giving it a key welfare role in the industry.
The union also became a founder member of the National Federation of Building Trade Operatives, and Otley served on its Emergency Committee.