Here is a fascinating report about a discovery at Hadrian’s Wall from perhaps the 4th-5th century. The Christian symbolism on the cup is fascinating, and equally fascinating is a Christian presence at Vindalanda, an original Roman fort on Hadrian’s Wall.
Thanks to my colleague Philip Jenkins for the heads up….
https://www.theguardian.com/uk-news/2020/aug/29/hadrians-wall-dig-reveals-oldest-christian-graffiti-on-chalice