The title Baron Henniker, of Stratford-upon-Slaney in the County of Wicklow, was created in 1800 in the Peerage of Ireland. The 4th Baron was created Baron Hartismere, of Hartismere in the County of Suffolk, in the Peerage of the United Kingdom in 1866; the two Baronies remain united.
The title BaronHenniker, of Stratford-upon-Slaney in County Wicklow, was created in 1800 in the Peerage of Ireland for Sir John Henniker, 2nd Baronet, of Worlingsworth, who had previously represented Sudbury and Dover in the House of Commons.
The 4th Baron was created Baron Hartismere, of Hartismere in the County of Suffolk, in the Peerage of the United Kingdom in 1866.
The town of Henniker, New Hampshire in the United States was named for the 1st BaronHenniker.