People would have been up in arms if China tried to arrest Chen Guangchen during his daring escape from house arrest. But the UK police are literally circling that wagons around the Ecuadoria embassy in anticipation of Ecuador granting asylum to WikiLeaks founder Julian Assange.
Here's a refresher: The Universal Declaration of Human Rights states that
Everyone has the right to seek and to enjoy in other countries asylum from persecution.(Article 14) Asylum is granted if you have a well-founded fear of political persecution, based on your political opinion, and the government is unable to stop it.
It would be completely contrary to the letter and the spirit of asylum for the UK to arrest Assange if he is granted asylum by Ecuador.
The United Nations 1951 Convention Relating to the Status of Refugees and the 1967 Protocol Relating to the Status of Refugees guides national legislation concerning political asylum. Under these agreements, Assange is a refugee--a person who is outside their own country's territory--owing to fear of persecution on protected grounds. Protected grounds include race, nationality, religion, political opinions and membership and/or participation in any particular social group or social activities.
Rendering victims of persecution to their persecutor (the UK arresting Assange to extradite to Sweden, which will promptly extradite him to the U.S., where he faces the death penalty) is a particularly odious violation of a principle called "non-refoulement," part of the customary and trucial Law of Nations.
These are the accepted terms and criteria as principles and a fundamental part in The U.N. 1951 Convention Relating to the Status of Refugees non-refoulement order.
If Assange is granted asylum in fifteen minutes, the UK should respect that. Asylum orders take precedence over extradition orders, especially when the pretextual extradition orders serves as one of the bases of the asylum application.