- Matthew Murray, engineer of Holbeck, Leeds
- Mary Murray, his gun-toting wife
- John Marshall, Leeds mill-owner and mentor of Murray
- James Fenton and David Wood, Murray’s business partners
- James Watt Senior, inventor, of Soho, Birmingham
- James Watt Junior, his son
- Gregory Watt and Matthew Robinson Boulton, their partners in Boulton, Watt and Sons
- William Murdoch and Abraham Storey, Boulton and Watt’s loyal lieutenants
- Dixon, Halligan, Hughes Senior and Junior, the disloyal workforce
- Benjamin Gott, Leeds mill-owner and ally of Watt
- Nicholson, Upton and Weston, lawyers