The Marquesses of Hertford are members of the Seymour family headed by the Duke of Somerset.

In 1712 he was created Baron Conway of Killultagh in the Peerage of Ireland.

In 1750 his son Francis Seymour-Conway, 2nd Baron Conway, was created Viscount Beauchamp and Earl of Hertford.

[2] These were revivals of titles previously held by the Dukes of Somerset, which had become extinct the same year on the death of Seymour-Conway's kinsman Algernon Seymour, 7th Duke of Somerset.

The heir apparent is the present holder's eldest son, William Francis Seymour, Earl of Yarmouth (b.