Robert Downey Jr among 700 across the world wishing little Josh well

But 700 postcards have now flooded Josh Johns' home over the past week after well-wishers from across the world were touched by his plight.

The well-wishers have sent messages from across the globe. Postcards from far-flung places including Japan, Australia and Brazil have flooded through the letterbox of little Josh Johns' home in a week, bringing a smile to his face.

And now celebrities including Hollywood superstar Robert Downey Jr and former Doctor Who David Tennant have also lent their support to the seven-year-old – not to mention the 300 people who have posted pictures on social networking website Facebook.

The brave youngster is battling acute lymphoblastic leukaemia after being diagnosed with the life-threatening disease in March.

He is undergoing intensive treatment at Birmingham Children's Hospital, with up to three sessions of chemotherapy a week, and is too ill to travel away on holiday during the school break this year.

But his fight has received a boost from kind-hearted well-wishers the world over since his family launched the 'Postcards for Josh' Facebook campaign, which allows him to see the world from his home in Hixon, Staffordshire.

Since the page went up on July 27, Josh has seen the postman bring cards to his door every day – with more than 50 cards arriving on one day alone – while hundreds of people have uploaded pictures of exotic locations on Facebook.

They include former Coronation Street actress Julie Hesmondhalgh, who played Hayley Cropper.

She posted a photograph of herself holding up a card with the message: 'Always remember you are braver than you believe, stronger than you seem, smarter than you think'.

Other stars who have joined the campaign include David Tennant, Robert Downey Jr and rock band Scouting for Girls, all of whom have re-tweeted a plea for people to send cards.

Some of the most touching messages have arrived from complete strangers.

Like the postcard from Stanley Park, Vancover, with a totem pole on it. The message read: "Hi Joshua, I saw your picture on Facebook. I see you have a beautiful smile. Keep it on, OK. I am a paraplegic since I turned 21. I am now 60. Keep fighting. Its worth it. Good luck, Jacqueline."

Or the postcard featuring a snap of an RNLI lifeboat. The message was simple and to the point. It went: "To Josh, Get well soon. Love, Toby, aged 5.

Another arrived from Arizona that read: "Hi guys, I heard you could not go on holiday, so here is a post card from sunny Phoenix. It is so hot here you can fry an egg on the sidewalk. Hope you are doing OK and get well soon, from Martin Perry."

One of the more bizarre ones was sent from Key West by the Krout family and showed a cat with an unusual number of toes that belonged to the author Ernest Hemingway.

The idea was hatched when Josh's school, St Peter's Primary in Hixon, gave pupils a summer project to send postcards from wherever they went on holiday.

With Josh too ill to travel and requiring constant medical supervision, family members did not want him to miss out.

His uncle Matthew sent him a postcard while on a business trip to Texas and asked some of his friends to do the same.

Within days, postcards started landing on the Johns' family doormat, many of them featuring short messages of support. Josh liked them so much, the family set up the Facebook page, which garnered more than 4,000 likes in less than a week.

Josh's 43-year-old father, Jason, said at the family's home in Hixon, Staffs: "This all started because we had to cancel our planned family summer holiday because of Josh's treatment.

"So I asked his uncle, who travels a lot on business, to send him a postcard when he was next overseas.

"He did and suggested a couple of his friends did the same.

"After that it went crazy in such a short space of time. We have been overwhelmed by the response.

"We set it up on Facebook on the Sunday night and the first postcards started to arrive on the Tuesday.

Since then we have received more than 700 in a week. Luckily, the postman thinks it is a wonderful idea. And it is not just postcards. A lady in New Hampshire sent two of the Dr Seuss children's books that he loves.

"It was an absolutely lovely gesture. Somebody in Australia sent an Aussie rules football club shirt, while a man involved in renovating a Canberra bomber sent him loads of cards and badges along with an invitation to come and see the plane when he is well."

Josh is currently undergoing chemotherapy treatment two or three times a week until August 21 with this expected to be followed by eight weeks of slightly less intense chemotherapy.

He would then be expected to have a session a month for the following three years to ensure the disease is completely out of his system.

His father continued: "People seem keen to share things that they find interesting with him.

"Josh is so excited every time he gets a card through the door. He was at hospital after treatment and the first thing he asked me was 'have I had any more postcards?'

"It's wonderful that people are taking the time to do this. It is having a really positive effect on Josh.

"The community nurse saw him the other day and said he had not seemed so bouncy for a long time.

"The doctors and nurses at the hospital also think it is a great idea and have all promised to send him cards from their holiday.

Some of the postcards feature short 'get well soon' messages, while others document the stories of people who have battled through disease themselves.

Jason added: "We have received such a variety of messages.

"Children as young as four are sending cards, which is really touching.

"He had one from a guy who said he had been diagnosed with leukaemia as a child but now lives a healthy life in his 20s with a young child of his own. Josh reads them all, although we help him with handwriting at times."

Josh, who lives with dad Jason, his mother, Nikki, also 43, and siblings Kristian, 17, Bethan, 15 and Freya, 6, was diagnosed with leukaemia just before Easter.

His mother has given up her job running speech and language classes for the under fives because of Josh's vulnerability to infection and his IT worker father is now on statutory sick pay because of the amount of time spent caring for his son. He had been a perfectly healthy child but when he began suffering with back and leg pain his parents became concerned and took him to hospital for a blood test.

Soon after he started to get sharp headaches, then small purple spots started appearing on his body. The tests revealed the presence of acute lymphoblastic leukaemia, a cancer caused by the overproduction of white blood cells.

His father said: "We could tell something was wrong because he wasn't his usual self. It was complete panic.

"You don't expect anything like this to happen and you just ask yourself 'will he get better?'. We have tried to stay positive.

"The doctors have said he is responding very well to his treatment programme and we have complete confidence in the work they are doing.

"It has been a significant change in life for the whole family but we are all just getting on with it. A lot of positives have come out of this, such as the wonderful support from friends, family and total strangers the world over." Since his diagnosis Josh has had to get used to a new way of life in his battle to beat illness.

The everyday tasks which he used to find straightforward have become tiring and, at times, impossible. Jason added: "He has trouble walking and has lost all of his hair. He has not been able to go to school for quite some time and I think he misses that.

"The doctors have said he can go back to school next spring, which gives him something to look forward to, but for the time being his treatment is the priority.

"Not being mobile is really frustrating for him. He gets tired very easily but he doesn't really want to have to rest all the time. The doctors have told us the survival rate of children with leukaemia is 90 per cent. We will keep believing he will be okay." Jason said Josh's last lot of treatment had 'knocked him for six', making it difficult for the youngster to eat and causing a mild tremor in his hands, but added: "Hopefully he'll start to pick up in the next couple of days.

"But we are keeping his spirits up by reading him everyone's lovely messages, photos and postcards," he said.

Josh is now marking off the locations where his postcards come from on large maps of the UK and the world at his home. His dad added: "He loves it. So many people he doesn't know sending him their best wishes has really put a smile on his face. He has never met any of these people but in their own way all of them are helping him to get through this."