Royal Mail have revealed how children can write to Santa - and how they will have a guaranteed response from Father Christmas.

Here's everything you need to know.

How to send a letter to Santa with Royal Mail

The Royal Mail have brought back its special festival postal service which allows children to receive a free, personalised letter from Santa at Christmas.

Youngsters will need to post their Christmas wish lists to Santa and his elves by 11 December to get a reply before the big day.

Children must include their full name and address in their letter, and Father Christmas promises to send a personalised reply to everyone who wrote to him.

A message from Father Christmas reads: “Dear boys and girls, Christmas is a very exciting but busy time for me.

“The elves are making toys, the reindeer are practising their sleigh runs, and I'm busy preparing my list of who's been good this year.

“I will be getting my sleigh ready for the long journey on Christmas Eve and in between I will try to reply to as many of you as possible.

Where do I send a letter to?

To receive a reply from Santa in English, letters need to be posted to the following address:

Santa/Father Christmas, Santa's Grotto, Reindeerland, XM4 5HQ

For those who'd like a reply in Welsh, address your letter to:

Sion Corn, Ogof Sion Corn, Gwlad Y Ceirw, XM4 5HQ

Brothers and sisters can both send letters in the one envelope and will still receive an individual reply, although they can post lists individually if they would prefer.

Be sure to check the address is written clearly on the envelope and you will need to pay for postage to send the letter. However, a return envelope and stamp won’t be needed to receive a reply.

Royal Mail, which helps Father Christmas to deliver his replies, says that names and addresses won't be used for anything else and will be deleted after Santa has sent his reply.