No Children Allowed
Where babies and children are not invited, this must be clearly stated on the practical information supplied with the invitation.
Telling guests can be awkward, so diplomacy must be employed and reasons given.
It must be a blanket rule with a specific age cut-off (for example no under-eights).
No exceptions should be made, even for close friends or family.
Wording
The wording on the invitation's extra-information sheet could read, for example:
Unfortunately due to the limited size of Luxury Hall, we have decided not to invite children under the age of eight
Owing to the close proximity of the lake at Woodland Manor, we cannot invite children under the age of eight.
It is polite to include an extra sentence such as:
We hope that parents will look forward to a relaxing break and sharing our day with us.