thankyou: the legend is similar to others I have seen on pre-1801 coins.
The coat of arms - and I am no expert - looks sus to me because -
the French, Irish, and Hanoverian elements look OK, but the English element only has two lions passant, whereas three is the norm.
And, the crown doesn't look right.
I'm thinking that it might be a comemorative medallion, celebrating KG3's aoronation, issued privately, rather than a coin from
The Royal Mint ...