Constructed 1906 by Madras Railway as a 2ft 6in/762mm narrow gauge(NG) famine protection line from Morappur to Dharmapuri; extended to Hosur 1913 and renamed Morappur-Hosur Railway. The line is the property of the Government of India(GoI). 
The Morappur-Dharmapuri section was worked on behalf of GoI by the former Madras Railway Company up to 31st December 1907. Then made over to the South Indian Railway(SIR) Company for maintenenance and working.
The Dharmapuri-Hosur section was constructed by the SIR who were responsible for maintenenance and working.
Refer to FIBIS Fact File #4: “Research sources for Indian Railways, 1845-1947” - available from the Fibis shop. This Fact File contains invaluable advice on 'Researching ancestors in the UK records of Indian Railways' with particular reference to the India Office Records (IOR) held at the British Library
An on-line search of the IOR records relating to this railway  gives the following: -
- L/F/8/16/1147 “Madras Railway Company, Contract for construction and working of famine protection lines from Morappur to Dharmapuri and from Tripatur to Krishnagiri; 1904"
- L/F/8/17/1232 “South Indian Railway Company Limited, Contract as to construction and working of extension to Hosur of the Morappur-Dharmapuri narrow gauge line; 1909"