ELF on the Shelf has delighted children this Christmas but with the festive period drawing to an end it's time he reported back to the boss in red on who's been naughty or nice.

With elves about to leave little ones’ shelves, after a busy festive season, we look at what their goodbye letters could say.

5 It's a wrap: a mum covered her Mini Cooper in a bid to trick her kids and blamed her three elves on the shelf Credit: Caters News Agency

When does Elf on the Shelf leave?

Father Christmas is expected to pick up his little spy - the Elf on the Shelf - on Christmas Eve, when he flies back to the North Pole.

However parting with his scout is obviously too hard to bear for some people.

Several parents say on social media that the cheeky character stays till New Year's Day, as their kids "want as much time with him as possible".

5 A little girl was left in fits of giggles in a hilarious Elf on the Shelf hairy bra prank Credit: Liam Gilman

What should Elf on the Shelf's goodbye letter say?

Marking the grand finale of the elf's visit can be as simple or as elaborate as you want to make it.

Some leave a small present for children, on the morning of December 24, along with a short note saying they'll be missed and to try and be good for the rest of the year.

Parents on Mumsnet pondering how best to deal with their departure suggest leaving short poems about winter and Christmas cheer, or giving kids a photo of the elves waving goodbye from the pile of presents.

5 More mayhem here, after an elf on the shelf prank involved turning a bath into a giant hot chocolate, filled with marshmallows Credit: Caters News Agency

Yahoo! Lifestyle has the following suggestions:

Fill a Christmas Eve box with a holiday movie, popcorn and Christmas pyjamas for a cosy family night-in

Write a note saying the elves have gone wild, and needed to return to the North Pole for some time-out

Leave a new Christmas book from your elf, with a special message inside the front cover

For those with writer's block, Romper says glittery footprints could be left, heading towards the chimney or front door.

Or, write a short letter in flour sprinkled on your table.

Another great idea is to fill a clear, plastic Christmas tree ornament with a note from your elf.

5 Last year saw Kim Kardashian's daughter North killing her brother Saint's Elf on the Shelf and building a grave for it Credit: Instagram

Other Elf on the Shelf Christmas Eve ideas

Your elf could leave a postcard, bidding your kids farewell till the following Christmas.

Saying goodbye with marshmallows, or leaving a special present from them under the tree are other options.

Leaving a collage of photos, showing where the elf has been, is another nice reminder of the fun they've had in the run-up to Christmas.

What is Elf on the Shelf?

Elf on the Shelf is a toy which is sent by Father Christmas to watch over little children and make sure they're behaving properly over the festive period.

Parents are supposed to move the puppet around the house each day to create the illusion that he is popping up somewhere new and always reporting back to Santa.

The tradition was started in the US after Chanda Bell, an office secretary from Atlanta, wrote a children's book with her mum.

The Elf on the Shelf: A Christmas Tradition explains how Santa Claus receives nightly reports from elves who are posted to every household.

Elf on the Shelf has it's own official website, where elves can be purchased from £29.95 including the accompanying book.

5 Elf keeps track of who is naughty or nice Credit: Not known, clear with picture desk