When asked by a Sky journalist whether he would do the same again, father Brett King replied “of course” and added: “My son’s worth everything, worth me going to prison, worth everything, because they were going to kill him in England or turn him into a vegetable.”

Mr King also said that he and his wife Naghmeh had been “treated like terrorists” following the international manhunt to find them, sparked by their removing their five-year-old son – who has a brain tumour – from a Southampton hospital.

He also spoke of their torment at being left languishing in a Spanish prison unable to see their son, with no television and no understanding of why so many journalists were camped outside Soto del Real prison near Madrid waiting for their release.

British police dropped the case against them following an outcry against the treatment of Ashya’s parents, with Prime Minister David Cameron saying that he welcomed the prosecution being dropped and that “it’s important this little boy gets treatment and the love of his family”.

As they prepared to see their son today for the first time since being detained on Saturday, Ashya’s mother Naghmeh told the BBC that all she could do “was just cry and pray” while in her prison cell.

“I just want to wet his mouth because he can't drink through his mouth, I want to brush his teeth, I want to turn him side to side every 15 minutes because he can't move.

“I just want to do all those things I was doing from Southampton, I want to do it for him here.”

Brett King said that he wasn’t angry: “My heart is aching for my son and anger can't come in at the moment because I've just got these feelings that I've got to see my son's face.

He later added that he hopes “no other parent has to go through this rubbish.

“I would be happy to spend years in prison rather than my son be given treatment that’s going to kill him or disable him for the rest of his life,” he said.

Mr King also claimed that he and his wife had advised Southampton hospital that they were taking Ashya out, though the hospital states otherwise.

The Kings had taken their son to Spain with the boy's six siblings last week after the British hospital he was being treated in – following the removal of a tumour on 24 July – refused to give proton radiotherapy to the child – a special treatment requested by the parents.

“The Trust considers there is no benefit to Ashya of proton radiotherapy over standard radiotherapy. This view is supported by a national independent expert body,” a statement by the hospital says.

“Despite this, the Trust agreed with the family to refer Ashya for proton radiotherapy, as the family had indicated that they could fund it privately.

“On 28 August 2014, during unsupervised leave on the Trust's grounds, Ashya's family chose to remove him without informing or seeking the consent of medical staff.”

Ashya is now set to travel to the Czech Republic for the proton beam treatment his parents wanted him to get.

The boy’s medical records have been sent to the Proton Therapy Centre (PTC) in Prague, though he will reportedly have to travel back to the UK for two cycles of chemotherapy before undergoing the proton treatment on mainland Europe.

In a short press conference this morning in Seville, Mr King said: “Hopefully now we can see our son, we can be together and show love to him, because without that there is no purpose to life.

“We just want to help my son get through this bad time, because he hasn't got too many months to live. And we were locked away in a cell and no one can do anything.”

Ashya's brother Naveed has posted a number of videos to his YouTube channel explaining the situation and has also provided a number of links to help the family, including an IndieGoGo fundraising page which has so far garnered £22,000 in donations to go towards the child's treatment.