Debrett's etiquette adviser Liz Wyse says that both of them must come out.
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2.
The authority on etiquette, Debrett's, says traditionally, if you were not known by the bride's mother, you did not get an invitation.
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3.
"How one behaves when one meets the Queen is fairly self-evident and obvious, " said David Williamson, co-editor of Debrett's (the last word in social etiquette).