He was educated at Sedbergh School before admission to Queen's College, Oxford, where he matriculated in 1670.

[2] Prior to his creation as a viscount in 1696, Lowther had succeeded his grandfather as a baronet, and was twice member of parliament for Westmorland between 1677 and 1696.

In 1688 he was serviceable in securing Cumberland and Westmorland for King William III, and was appointed to the Privy Council in 1689.

Lonsdale wrote in 1688 a brief account of events from the accession of James II to the landing of the Prince of Orange at Torbay, which was later printed as Memoirs of the Reign of James II (in 1808, for private circulation) and again in 1857.

The Memoirs reveal no more of Lonsdale's part in events than his public utterances.