OLDHAMSTEAD, Benington, circa 1800
Oldhamstead is an interesting rare name, and like other rare names (eg Thrale, Burchmore, Seabrook in Right Name, Wrong Body) they are often associated with a geographically small area, sometimes a single village, and can be very common in that village.
The fact that John died in Hertingfordbury Workhouse clearly indicates poverty and this gives a clue to what records one might expect to find.
Graves: I don't know the Benington church, but many churchyards have been cleared and where the memorials are untouched there are few gravestones from 200 years ago - and most of that age are now unreadable.. Gravestones cost money - and as there are no local rocks suitable for making tombstones in Hertfordshire - the stone would have to be brought from elsewhere. The commonest form of memorial was the grave board. (see Hertfordshire Churches & Other Places of Worship. Because they were made of wood (usually oak) very few original boards have survived in a very weathered form - and none with the original text. An even smaller number have been regularly renewed. Paupers would have been buried in an unmarked grave.
Abode: If members of the family were still in the village in 1840, their house will probably be identified in the 1840 tithe returns, and you might be able to tie it in with the 1841 census. Before that, if they lived in a copyhold property there could be information of the occupation and transfer of the property in manorial records (if the records have survived and are accessible). However such records may not identify the exact location. Land tax and rate records may record the presence of Oldfield - but usually do not identify the location. If you can establish that your ancestors had a distinctive occupation (such as miller, blacksmith or baker) it may be possible to identify the building from its use. You should realise that many of the older poorer properties will have been demolished by now, and if still standing and "un-restored" would be considered unfit for human habitation!
Because the survival of records can vary from village to village you will almost certainly need to find out what HALS holds, and before visiting Hertford it would be a good idea to read Tracing Your Family History in Hertfordshire.
There is a web page for Benington
If you can add to the information given above tell me.