You must forgive me for being a pedantic b*****d Flintstone, but it is bad form to toast Her Majesty as the Duke of Lancaster, anywhere except in the county itself.And that's from someone whose correct Loyal, after dinner toast to the Monarch, remains "To the Duke of Lancaster".
At formal dinners, when we used to toast “The Queen” our resident Lancastrian would add “The Duke of Lancaster” to be followed by the rest of us bellowing “ shut up Harold”. It happened so often, it became a tradition. Very sadly the said Harold died quite recently.
ps According to Debretts, which you will understand that I spend all my spare time studying 😉, The DoL toast may be given elsewhere in the country but only at Lancastrian events...😴😵😴😵