Parliament re-established the militia as a local defence force in 1757 to counter the threat of invasion from France. An Act set out the procedures for raising the militia. From time to time constables were ordered to draw up lists of all the able-bodied men between 18 and 45 in their parishes. A ballot was then held to decide which of these men should be called upon to serve or else pay for a replacement. The militia never saw active service, but the institution survived until the threat of invasion receded after the Napoleonic wars. The lists for Pirton survive from 1758 until 1786.
The lists note name, rank or occupation, and any incapacity. Those excused service included peers, clergymen, apprentices, seamen, soldiers, those who had served previously and constables. Exemption from service was also granted on the grounds of poverty and infirmity for it was held that, if such men served, their wives and children would have to be provided for out of the poor rate.
Hertfordshire Militia Lists are deposited at HALS Hertford.