Lancelot and his wife Jane, are mentioned in the Responsa Scholarum of the English College, Rome Part 1 1598-1621. This is possibly because their son studied here.
A family tree provided in The Machells of Crackenthorpe mentions three sons: the eldest Protestant, the second, Catholic and Rev. George aka "Launcelot of Cumberland". No mention is made of a third son, Leonard, who would have been the eldest but who married a Catholic. As such the two source documents are in conflict on this point.
A probate inventory for a Lancelot MACHELL of Appleby dated 1598 exists in the Carlisle probate records.
