He was admitted at Middle Temple in 1689 and matriculated at Trinity College, Oxford on 4 April 1690.
[1] Lennard joined the army and was a captain in the Earl of Denbigh's Dragoons from 1696 to 1697.
In 1713 he was lieutenant and lieutenant-colonel and in 1714 appointed groom of the bedchamber to the Prince of Wales, a post he held until 1717.
[2] At the 1715 general election Lennard was returned as Whig Member of Parliament for Hythe on the interest of the Lord Warden.
[2] His alleged illegitimate son Samuel was born by Mary Johnson at Maskell's house in Great Ormond Street, London on 10 September 1720.