This section is from the book "Lessons In English", by Chestine Gowdy, Lora M. Dexheimer. Also available from Amazon: Lessons in English.
Invitations to formal dinners, luncheons, and other entertainments are sometimes written in the third person. Replies to such invitations should correspond to them in form. Invitations in the third person are less common than formerly; but since they are sometimes used, it is well to recognize them, and to know the proper form of reply. Invitations on the part of an organization, such as a class or a club, are written in the third person.
Notice in the following illustrations that neither I, we, you, nor your is used.
Mrs. George White requests the pleasure of Mr. and Mrs. Lloyd's company at luncheon on Friday, October twelfth, at one o'clock, to meet Miss Sanford.
105 Third Street, Tuesday, October ninth.
Mr. and Mrs. Lloyd accept with pleasure Mrs. White's kind invitation to luncheon on Friday, October twelfth, at one o'clock.
Wednesday, October tenth.
Mr. and Mrs. Lloyd regret that illness in the family prevents1 their accepting Mrs. White's kind invitation to luncheon on Friday, October twelfth.
Wednesday, October tenth.
1 Notice that though the luncheon is in the future, the declination is present. The mistake of using the future phrase will prevent is sometimes made.
 
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