13 was shared by Peachy Proctor, Jess Cameron, Delia Watts, and Mary Fergusson.

There was, therefore, little doubt but that she was to be received into the secret society of whose existence she had already gathered some hints.
"I'll be there at 8.10," she whispered to Peachy, as they trooped into the French class.
"Right-o!" replied that light-hearted damsel.

"Just one warning--don't be scared at anything that happens; it's all in fun! Don't say I told you, though.

No, I can't explain.

I'm not allowed.