Robert Keyes was the son of a Protestant clergyman though his mother came from a Lincolnshire Catholic family, the Tyrwhitts. Through his wife he was connected to Ambrose Rookwood and was associated with Lord Mordaunt, a Catholic peer.
He seems to have been drawn into the plot late in October 1604 and his role was to look after the gunpowder and other equipment stored for a time in Thomas Percy's house in Lambeth.
He left London on the morning of 5 November but was not at Holbeach House in Staffordshire on 8 November. Captured soon afterwards and tried on 27 January 1606 he was executed in Old Palace Yard on the 31 January. He was said, from the scaffold, to have defiantly insisted that the plot had been justified.
John Grant came from Warwickshire, where he owned Norbrook, a house not far from Stratford-on-Avon, which was regarded by the conspirators as a valuable and strategically placed stronghold.
He was married to Dorothy, sister to the Winter brothers, and, like Catesby, Tresham and the Wright brothers, had been involved in the rebellion in 1601 led by the Earl of Essex against the dominance of Robert Cecil, Queen Elizabeth’s chief advisor.
Brought into the plot in March 1605, at around the same time as Christopher Wright and Robert Winter, he seems to have bought a number of weapons over the course of 1605. On 4 November he joined others, including Everard Digby, at the pre-arranged rendezvous in Northamptonshire.
Grant was with the other conspirators at Holbeach House, and was blinded in the gunpowder accident. He was captured and brought to London, tried on 27 January and executed in St Paul's Churchyard on the 30 January.