Unable to attend the birthday party :
12, XYZ Road,
New York ,
USA
12, January, 200*

Dear Ron
It was very nice of you to have invited me to the birthday function of your son on 3rdJanuary. I wish I could attend this function and enjoy meeting everyone but regret to say that because of an urgent pre-scheduled meeting with a foreign dealer, I shall be out of town on the day.
However, I and sending herewith a gift for Peter, I think he will like it. Please convey ‘my birthday wishes’ to Peter.

With regards
Yours sincerely
John