Solid evidence that a crime has taken place should be submitted before a Briton is extradited to another country.
The US-UK Extradition Act 2003 allows the US to extradite Britons who committed an offence under American law, even though the offence may have been committed in the UK by a person living and working in the UK. Famously used during the "NatWest Three" extradition, the US is only required to demonstrate "reasonable suspicion" that a crime took place, not prima facie evidence that it did.
Further, the act was brought in with a minimum of parliamentary scrutiny, under alleged secrecy.
The requirement to provide prima facie evidence that a crime has been committed before extradition should be restored.