Hope for Royal Brompton campaigners

But Mr Burns told MPs in parliament: "The consultation literature specifically asks consultees for their views on how many centres it is best to have in London, two or three.

"If they agree that two is optimal, they are asked to state which two they prefer, including the Royal Brompton.

"Although the Royal Brompton has not been included in any of the four proposed scenarios for child surgery units, people who are taking part in the consultation process can argue its case.

"The review remains flexible and open-minded as to the final number, and is happy to listen to all options."

His comments came as parents and children who had used the world renowned unit, marched on Downing Street to try and save the threatened services.

Trudy Nickels, from the Brompton Fountain, a charity supporting the hospital, said: "Children's heart surgery is highly complex and requires specialist expertise.

"The Royal Brompton is a world class centre and its expert doctors have saved and transformed the lives of thousands of children.

"Parents like me can testify to the excellence of its care. We can't begin to understand why NHS managers would want to remove this service and risk seriously undermining the availability of quality care for vulnerable children in London."

Children and parents who have experienced the care of the hospital first-hand took the petition to 10 Downing Street, along with Greg Hands, MP for Chelsea, who added: "Royal Brompton is recognised as a centre of excellence that has pioneered many life-saving techniques.

"I have been overwhelmed by the concerns raised by parents and families who cannot understand why NHS managers are proposing to destroy a world class service that has transformed many thousands of lives.

"I hope that they will listen to people's concerns now."

The Safe and Sustainable review consultation closes on July 1, after which a decision on the unit will be made.