How do you say "bring a plus one"?

The simplest and most common phrasing is 'plus one'. You might write 'Mr A Smith and guest' on the envelope, or 'Mr A Smith and a plus one'. For a more personal touch, 'You are welcome to bring a partner' works well if you know the guest has one. If you are unsure about their relationship status, 'a guest is welcome' is neutral and kind.

Be clear about who the invitation is for. If you only mean the named person, address the envelope to them alone. This avoids confusion without needing to say no outright. For children, say 'and family' or list each child's name if they are invited.

If you are worried about phrasing, keep it short and direct. Your guests will understand 'plus one' perfectly. It is the standard term used across the UK for an unnamed accompanying guest.