It was created in 1937 for the Conservative politician Sir George Hennessy, 1st Baronet.
[2] His eldest son, the second Baron, was a Brigadier in the Grenadier Guards.
In 1999 he was created a life peer as Baron Hennessy, of Windlesham in the County of Surrey, so that he could continue to sit in the House of Lords after the passing of the House of Lords Act 1999, which removed the automatic right of hereditary peers to a seat in the upper chamber of parliament.
[3] As of 2015[update] the titles are held by his son, the fourth Baron.
The heir apparent is the present holder's son Hon.