As the Norwich City Council explains, it is illegal for people under 18 years of age to get a tattoo, based on the 1969 Tattooing of Minors Act. The law does not include any exceptions for getting a tattoo based on parental consent.
The Preston City Council advises tattoo artists check a valid identification document, such as a passport or driving license. Prosecutions can proceed even if the tattoo artist is not aware that he is working on a minor. Enforcement of tattoo age restrictions is performed by the local police. The Vale of Glamorgan Council further details that an exception to tattoo age restrictions is available for qualified medical practitioners carrying out a tattoo for medical reasons.