Baggerley was in the service of James Stanley, 7th Earl of Derby. He was employed in the embarkation of that nobleman in the Isle of Man on 12 August 1651. On 13 October the Earl applied that Captain Baggerley, who was then a prisoner at Chester, might be allowed to attend him during the few hours he had to live. The request was granted, and it is to Baggerley's pen that we are indebted for a minute and touching narrative of the Earl's final hours and execution. This narrative has been printed by Draper in his account of the "House of Stanley", 1864.[1][2]
Draper, Peter (1864). "Trial and Execution of James, Earl of Derby". The House of Stanley; Including the Sieges of Lathom House, With Notices of Relative and Co-Temporary Incidents &c. T. Hutton. pp. 202–223.