William JULIÉ explains that once a court decision granting extradition has been issued, the UK Government must sign an extradition decree within two months except if there is a ground justifying a refusal to sign, which is not the case here.
An appeal of this decree before the High Court is possible. Julian ASSANGE could also lodge a claim based on article 39 before the ECtHR to request the suspension of the decree but a favorable decision is very hard to get and works only when a risk of violation of article 3 of the Convention is demonstrated.
A previous judgment from the ECtHR asked Belgium not to extradite an individual, however Belgium still proceeded with the extradition.