I am unable to attend because of a previous engagement.
Queen Elizabeth: We would love to, such a treat, but alas… a previous engagement. What a pity.
previous engagement
I'd love to, but I'm afraid I have a previous engagement.
Be sure to provide yourself with some previous engagement which shall have a semblance of probability, and communicate the fact to me by a line in writing.
Sorry. I can't do lunch with you. I have a previous engagement. ;
Thanks, but I have a previous engagement.
To have a previous engagement
I can't see you on Monday because I have a previous engagement.
So have the Spring Festival holiday this thing needs attention, confirmed in advance to also have a previous engagement under the premise of.
It is so thoughtful of you to ask me, but unfortunately I have a rather important previous engagement on that day.
