Caitlin bruises easily and is vulnerable to infections

The latest testing session to find a match for Caitlin Behan is on 6 January at Daventry Fire Station, Northamptonshire.

Caitlin, of Weston Favell, suffers from a rare condition called Fanconi's Anaemia, a potentially fatal disease which prevents the bone marrow from producing blood cells normally.

Her father Mark, a sergeant with Northamptonshire Police, said: "I'm sure there is a donor out there.

"She desperately needs a bone marrow transplant - ideally within the next six to 12 months; nothing else will cure her."

Even if they are not a suitable donor for Caitlin, there are many other people out there desperate for this kind of help Mark Behan, father

Caitlin has a rare tissue type which is proving an obstacle to finding a match.

Mr Behan said: "She is becoming increasingly conscious that she becomes ill but she is tough as old boots, she's a great girl."

More than 1,000 people have been tested at three public surgeries, but no match has been found.

When the Anthony Nolan Trust held a special clinic at Northampton Police Headquarters for staff to be tested more than 400 people responded.

Mr Behan said he had been "overwhelmed" by the number of colleagues who came forward to offer their help.

"I would like to appeal for other members of the public to come forward. Even if they are not a suitable donor for Caitlin, there are many other people out there desperate for this kind of help," he added.

The Anthony Nolan Trust is a register of volunteers willing to donate bone marrow where a match cannot be found within a patient's family.