From Graces Guide
1786 Matthew Boulton struck 100 tons of copper coins for the East India Company.
1788 Boulton approached the British government with a proposal for minting low value coins by machine, as an improvement on the hand-made process then in use. This would help to alleviate the shortage of copper coins in Britain and would cost less. Samples were available in May although the first order from the government did not come for 10 years. Boulton built the first steam-powered mint, near to his manufactory at Soho (grid reference SP051890) in Handsworth, near Birmingham, taking sheet and strip copper from there.
Business in manufacturing coins, medals, tokens and mint machinery came from the colonies and elsewhere. The mint contained eight machines, driven by steam engine, each capable of striking 70 to 84 coins per minute.
In addition to copper domestic coins, silver coins were made for some of the colonies, and various medals were struck, a grand total of 600 million.
1809 After Matthew Boulton's death, the Mint was directed by Matthew Robinson Boulton.
1841 MRB's son Matthew Piers Watt Boulton took over from his father until it closed in 1850
1850 On 1 April, the auction was announced of equipment from the defunct Soho Mint. Some of the machinery was bought at auction by the new Birmingham Mint of Ralph Heaton II.
A Detailed Account
A thorough study of the successful development of the Soho Mint by Matthew Boulton was undertaken by Sue Tungate for her PhD thesis, which is available online 
Sources of Information
- 'MATTHEW BOULTON AND THE SOHO MINT: COPPER TO CUSTOMER' Ph.D. Thesis by Sue Tungate, 2010
-  Wikipedia
- The Lunar Men, by Jenny Uglow, Faber and Faber, 2002