Searching his name on tinternet produces many interesting hits, he was an active public speaker with regard to the rights of miners, and was Secretary of one of their first Trade Unions, known as the Miner's Agent.

eg
http://www.fweb.org.uk/local-history/7-Books_on_the_Forest_of_Dean
(Recommended reading!)
http://way-mark.co.uk/foresthaven/historic/cinwesl1.htm
http://richardnet.co.uk/genealogy/bapchap.htm
http://palaceofmemory.co.uk/the-life-labours-and-ghosts-of-a-forest-collier-by-kirsty-h...

"Some societies, including at least two formed by miners at large pits, met at chapels, and several, notably the East Dean Economic Benefit Society formed at the Baptist chapel in 1854 by Timothy Mountjoy, promoted temperance."
From: 'Forest of Dean: Social life', A History of the County of Gloucester: Volume 5: Bledisloe Hundred, St. Briavels Hundred, The Forest of Dean (1996), pp. 381-389.
URL: http://www.british-history.ac.uk/report.aspx?compid=23270
Date accessed: 07 January 2014.

"By the mid 1850s production at larger collieries and other industrial works was occasionally disrupted by strikes. (fn. 66) A miners' committee at Cinderford in 1870 had contacts with other coalfields, and following strikes led by buttymen at Trafalgar and Parkend collieries in 1871 an association of Dean miners was formed and affiliated to the Amalgamated Association of Miners. Despite opposition, notably from the Baptist minister and former colliery owner Thomas Nicholson, the union was strongly supported in the coalfield and by the time of its second annual demonstration in 1873 the Dean branch had 13 lodges in the Forest. The union, for which Timothy Mountjoy was the local agent, attempted to protect the interests of both buttymen and daymen."
From: 'Forest of Dean: Industry', A History of the County of Gloucester: Volume 5: Bledisloe Hundred, St. Briavels Hundred, The Forest of Dean (1996), pp. 326-354.
URL: http://www.british-history.ac.uk/report.aspx?compid=23267
Date accessed: 07 January 2014.

and

"Another Nonconformist who made his mark politically in the Forest was Timothy Mountjoy (1842-1896). He regularly attended Littledean Hill Chapel Sunday School where he soon developed an aptitude for public speaking. Later he established a number of Friendly Societies for the miners, and acted as chairman of a Cinderford Ratepayers’ and Voters’ Committee. This led to the formation of a Miner’s Union and Timothy’s appointment as its first agent."
From this pdf file document
http://intranet.yorksj.ac.uk/potter/Power%20of%20the%20Chapel%20text.doc

He regularly attended Littledean Hill Chapel Sunday School where he soon developed an aptitude for public speaking. Later he established a number of Friendly Societies for the miners, and acted as chairman of a Cinderford Ratepayers’ and Voters’ Committee. This led to the formation of a Miner’s Union and Timothy’s appointment as its first agent.

FOUR PERSONALITIES FROM THE FOREST OF DEAN

Ralph Anstis - Four biographies of personalities from the Forest of Dean's past, Sir John Wyntour, a Forest businessman, Catharina Bovey, young widow of Flaxley Abbey, Timothy Mountjoy, Forest Miner and Sir Charles Dilke, M.P.

Paperback £9.99 316 pages Illustrated

Rosanne Mountjoy 56 Widow
Timothy 15
Amelia 9
all born in county

1851 East Dean
MOUNTJOY Timothy 26 Coal Miner East Dean
Caroline 25 Cambridge

1861
Timothy Mountjoy abt 1825 East Dean, Gloucestershire, England Head East Dean Gloucestershire

1871
Sarah Mountjoy abt 1824 Norcester, Cropthorne Wife East Dean Gloucestershire
Timothy Mountjoy abt 1823 Little Dean, Gloucestershire, England Head East Dean Gloucestershire

1881
Sarah Mountjoy abt 1825 Cropthorn, Worcestershire, England Wife Cinderford, Westbury On Severn - East Dean, Gloucestershire, England
Timothy Mountjoy abt 1825 Cinderford, Gloucestershire, England Head Cinderford, Westbury On Severn - East Dean, Gloucestershire, England

1891
Mountjoy, Sarah abt 1825 Cropthorne, Worcestershire, England Wife East Dean Gloucestershire
Mountjoy, Timothy abt 1825 Little Dean, Gloucestershire, England Head East Dean Gloucestershire
Mountjoy, Flora A abt 1856 Cinderford, Gloucestershire, England Visitor East Dean Gloucestershire

1901
Annie B S Meredith abt 1879 East Dean, Gloucestershire, England Daughter East Dean Gloucestershire
Clara E Meredith abt 1854 Hiley, Yorkshire, England Wife East Dean Gloucestershire
Reuben Meredith abt 1847 Littledean, Gloucestershire, England Head East Dean Gloucestershire
Sarah Mountjoy abt 1825 Cropthorne, Worcestershire, England Mother-in-law East Dean Gloucestershire