The best place for searching medieval stuff in or around the Durham area is here...
Link Here's the book 'liber vitae' for Durham.
LinkCan i join the club? I've recently gone medieval, i think!...

I originally started the family tree many years ago to see why my grandfather's name 'Rewcastle Armstrong' came from, after some time i discovered the first 'Rewcastle Armstrong' born in 1776, to John Armstrong and Ann Rewcastle. John and Ann were married in 1768 at Hexham, Northumberland.
Ann's grandfather Nicholas Rewcastle lived at Fallowfield and Cocklaw in the parish of St John Lee, within 5 1/2 miles from Hexham, Northumberland.
I have a basic tree going back to a marriage in 1596 when the Rewcastle's were still living in the same area, recently i have found Roger Rewcastell, John Rewcastell, Mylles Rewcastell in the muster roll for 1538 at Keepwick, in the Parish of St John lee, Northumberland. Keepwick used to be a medieval village, it is now a farm and is located 3 fields from Cocklaw.
The first recorded person with the name of Rewcastle (or various spellings of it), was William de Ruecastle mentioned in the 'Ragman Rolls' in 1296. There was also another, or possibly the same William de Roucastell mentioned in the Great seal of Scotland as receiving a pension from King Robert Bruce (1306-1329).
Last night i found John of Ruecastle mentioned in charters of the burgh of Peebles (1458 -1476), 62 years earlier the the Rewcastell's at Keepwick.
The location of the place Ruecastle where the surname came from is just outside Jedburgh, it lies approx 50 miles north of Keepwick, Northumberland and the road adjoining Keepwick/Cocklaw is called the Jedburgh road.
Rewcastle.