British History Online is the digital library containing some of the core printed primary and secondary sources for the medieval and modern history of the British Isles. Created by the Institute of Historical Research and the History of Parliament Trust, we aim to support academic and personal users around the world in their learning, teaching and research.

The main resources on British History Online for people researching local and family history for Hertfordshire are the Victoria County History of Hertfordshire (unfortunately only three of the four volumes) and the 1880s large scale Ordnance Survey maps of the county.

The site also contains images on the large scale Ordnance Survey maps of Hertfordshire

In addition there is a great variety of other sources, particularly relating to medieval records which are either available online - or where the calendar of documents held elsewhere is available. You never know what might turn up. I did a search for the tiny hamlet of Gubblecote and got two references to the Victoria County History of Hertfordshire and one to the Calendar of Papal Registers Relating to Great Britain and Ireland, Volume 9 (1912)