When Arthur Randall was born a year ago today, the usual tests didn't show anything untoward, and he was seemingly fit and healthy.

This unfortunately turned out not to be the case however, when, at just three months old, he began to vomit violently three to four times a day.

This sickness led to severe weight loss, and an emergency visit to Tunbridge Wells Hospital for him and his parents in January this year.

Tests revealed that Arthur had blood oxygen saturation levels of 73%, which baffled doctors, who couldn't believe he was still active with such low oxygen levels.

The human body is supposed to have oxygen saturation levels of 95-100%, and levels of 90% are usually considered to be dangerous.

Arthur was still so active and happy that clinicians changed the machine twice to make sure the readings were correct, but unfortunately they were.

The three-month-old was then given oxygen until his levels returned to normal.

In the weeks that followed, the baby underwent numerous tests, with many possible diagnoses being suggested.

Sadly for his parents, Ben and Alice, however, consultants couldn't tell them what was wrong with their baby.

Arthur was transferred to Royal Brompton Hospital in London for further tests, and doctors speculated that he could have interstitial lung disease, a condition which prevents oxygen passing into the bloodstream correctly.

Despite this tentative diagnosis from the hospital, something still wasn't right, as Arthur's T-cell count was very low.

T-cells are one type of cell involved in the immune system. The three-month-old's low count of these cells meant that his body could not fight off infections.

Arthur was then taken to Great Ormond Street Hospital for more specialised tests, and doctors found that he had Severe Combined Immune Deficiency (SCID).

This rare condition means that he was born with a severely malfunctioning immune system.

The family was transferred permanently to Great Ormond Street, where Arthur was placed in an isolation ward.

Ben Randall described how the family came to terms with their only child's illness.

"When we finally had a definitive cause for his sickness we felt a huge relief. Finally, there was a known condition, something that he could be treated for.

"But it was only as the hours and days passed that the reality of what SCID meant diffused through us.

"The feelings of fear, despair, and unfairness began to creep in like a liquid slowly working its way through our core."

Thankfully for the family, who live two hours away from Great Ormond Street in Tunbridge Wells, they were offered free accommodation by the Sick Children's Trust.

This trust believes that parents of sick children should have access to free, comfortable accommodation close to their child's hospital for the duration of the treatment.

Mr and Mrs Randall were given a room at Guilford Street House, just five minutes walk away from their son's bedside.

"Their kindness reduced the stress dramatically at what had been an already very stressful time for the previous three months.

"It allowed us to support each other, to wash and dry our clothes, and live a relatively normal life in an utterly abnormal time," Mr Randall said.

Arthur was given chemotherapy to kill off the malfunctioning cells in his body, before being given a bone marrow transplant.

The new bone marrow will create new cells that should be fully functioning.

Arthur, who turns one today, is responding well to the treatment.