[2][1] Lindsay served as Custos Brevium of the Court of King's Bench and from 1758 to 1776 was captain of a company of the 3rd Regiment of Foot Guards, a traditionally Scottish unit.

[1] As was the tradition, he continued to receive advancement in army rank, though he remained nominally a guards captain, and on 30 January 1776, he was appointed colonel of the 59th Foot.

In October 1778, he was commanding troops based at Warley, established as a safeguard against French invasion, when the camp was inspected by George III.

[7][8] He seems to have viewed the appointment with some despair and remained in London for a month, attempting to secure a meeting with Lord Amherst, commander-in-chief of the forces.

[11] Later in the year Lindsay wrote that he believed he had brought about a significant improvement in defences and had the support of the distinguished general Charles Grey in the matter, but by 2 September had offered his resignation.

In November John Robinson, the secretary to the Treasury, feared a parliamentary enquiry into defensive preparations against the Armada would call Lindsay to testify, who would reveal the unpreparedness of Plymouth for defence, and possibly cause the downfall of Lord North's government.