Copper Beaker made by Keswick School of Industrail Art (uk) 1900

This is a Beaker made in copper (size 4.5"x4.5"top ,3"base inches) from around 1900 by the Keswick School of Industrail Art . This school was a Very Important unit during the English Arts and Crfts Movement . It`s always a problem do you clean or do you leave well alone ? The KSIA as it was know is located in the English Lake District in a town call Keswick at the head of Lake Derwent Water .