Yes, thanks for the pic that now confirms my thought of yesterday. This pic above depicts (in the two middle lines) what is known as the “Wellington Declaration”, RELIG:PROT:LEG ANG:LIBER:PAR (to uphold the Protestant Religion, the Laws of England, and the Liberty of Parliament).
Charles I was a colorful monarch who got caught up in the Civil War, and eventually got beheaded for his actions.
What is the diameter(mm) and weight (gm) of your coin? It's a beauty and, assuming its real, quite valuable in both monetary and historic terms.
Don...