Tricky one, mermaid, since it partly depends on what you
want to happen.
If they got a sympathetic judge who took the child's wishes into consideration (and especially if the couple were saving the child from an abusive situation in the orphanage), then they could all live happily ever after - maybe with a suspended sentence for the kidnapping and home visits from the local social services to check on the child's welfare, before allowing the child to be officially adopted.
A lot of children run away from orphanages, with minimal police investigation and zero reporting in the media.
Probably, as soon as the child was identified - say during a visit to hospital - the doctor would phone social services and the police. Assuming the child is under 16, a Social worker would place the child in foster care (with foster parents) while the police investigated the circumstances of the child's abduction (the couple could simply claim the child ran away from the home and they took it in, which would not be kidnaping).
The couple could be placed in jail, (or released on bail if the police have no reason to suspect sexual abuse), while the police investigations continued. If sexual abuse was suspected they would probably be kept in jail in the lead up to the court case - which could be months.
- NaomiM
Sentencing for kidnap: up to 18 months (probably out in 6 months).
http://www.sentencing-guidelines.gov.uk/docs/complete_compendium.pdf
Kidnapping
Kidnapping may also be relevant in the context of s.62 of the Sexual Offences Act 2003
which makes it an offence to commit an offence with the intention of committing a sexual offence.
R v Spence and Thomas (1983) 5 Cr.App.R.(S) 413
Guidelines
Current Sentencing Practice Reference: B3-4
Circumstances Guideline sentence
1. Violence or firearm used, exacerbating More than 8 years’ imprisonment features such as detention of victim
over long period
2. Carefully planned abductions, victim Seldom less than 8 years’ imprisonment used as hostage, or ransom money
demanded
3. Scarcely kidnapping, perhaps the Up to 18 months’ imprisonment sequel to a family tiff or lovers’ dispute<Added>Oops, that last bit got screwed up:
Circumstances Guideline sentence
1. Violence or firearm used, exacerbating features such as detention of victim over long period: More than 8 years’ imprisonment
2. Carefully planned abductions, victim used as hostage, or ransom money demanded: Seldom less than 8 years’ imprisonment
3. Scarcely kidnapping, perhaps the sequel to a family tiff or lovers’ dispute: Up to 18 months’ imprisonment