Thmyl Fysbwk Layt Andrwyd 2.3.6 – Safe

On the back, handwritten: "Thmyl fysbwk layt" — code for: "They will forget you last."

Given the last part "andrwyd 2.3.6" , that looks like a version number or coordinates. "andrwyd" could be "and ruwyd" or "and rwyd" ? rwyd → rwyd might be "rwyd" as in "rywd" ? Could be Welsh: "and rwyd" (and net?) but "thmyl" doesn't fit Welsh easily. thmyl fysbwk layt andrwyd 2.3.6

So here it is:

A common assumption is that each word might be shifted by a certain number in the alphabet (Caesar cipher) or encoded with a simple substitution. On the back, handwritten: "Thmyl fysbwk layt" —