does the following say in the 20th year of Edward I?
"Dat. apud Lanc. die mercurij prox. post festum sancti Marie Magdalene anno regni Regis Edwardi vicesimo"
I figured it said the date of the Lancaster grant was the Wednesday after the feast of St. Mary Magdalene in the reign of King Edward I", but couldn't figure which year. Google Translate gave an amazing translation for the quoted text (smarter than I thought it could be):
"Dat. In Lancaster. on Wednesday next. the three and twentieth year of the reign of King Edward, after the feast of St Mary Magdalene"
I don't see where it gets the "three" for the 23rd year (vicesimo alone is translated as 20th). And then I refreshed and it dropped the "three and".
The Latin quote is from one of the sources given for Elizabeth de Samlesbury: "Remains, historical and Literary, Connected with the Palatine counties of Lancaster and Chester," page 121 - https://books.google.com/books?id=HP0MAAAAYAAJ&printsec=titlepage#v=onepage&q&f=false
It includes a footnote with genealogical info, but I can't tell the source of the info in the footnote, so I'm trying to pick up what info the Latin contains under the section that I believe refers to a charter of land for Robert de Holand.
ps - cool source: http://www.medievalgenealogy.org.uk/guide/chron.shtml