A courageous little girl undergoing vital treatment in Seattle in her ongoing battle against leukaemia is turning six years old later this month – and her family have a big favour to ask to make her special day even more memorable.

Erin Cross’ loved ones are inviting members of the public to send birthday cards across the Atlantic to the youngster to help her celebrate the milestone on August 23.

The Chester youngster has travelled to the North American city with her parents Sarah and Antony for the pioneering Car T Cell therapy – which is only available in the USA – which will make her eligible for a bone marrow transplant and give her the chance she desperately needs to beat her lymphoblastic leukamia.

Erin pictured at Seattle Children's Hospital

The community has rallied once before in aid of the schoolgirl, with the hundreds of thousands of pounds raised to fund the treatment making national headlines, and her auntie Kim Mylchreest is hoping it will pull together again to give Erin a very special delivery on her birthday.

Kim told The Chronicle: “They are very grateful to be over there and everything is going well at the moment but they are homesick so these cards will help to bolster them.

“Erin has a really cracking sense of humour for a little girl so she’d like anything funny.”

If you would like to send a birthday card, address it to Erin Cross, Ronald McDonald House 5000, 40th Avenue NE Seattle, WA 98105.

It is estimated that any post will take between seven to 10 days to reach there.