Britain Recognizes Spain’s Civil Unions. How Come The Reverse Isn’t True?

“In Britain, Schedule 20 of the Civil Partnership Act 2004 lists Spain as a country from where a same-sex marriage is to be recognized as equivalent to a British Civil Partnership. If a same-sex couple married in Spain move to Britain they have the right to deposit a copy of their Spanish Marriage Certificate with an official translation into English with the British General Registry office, although this is not compulsory and will not affect their rights to be treated as Civil Partners in Britain. […] In Spain, the Ministry of Foreign Affairs agreed on 16th November 2007 in a “Nota Verbal” addressed to the British government that a British Civil Partnership is to be recognized for all legal purposes as equivalent to a Spanish same-sex marriage. However, there is no provision for a British Civil Partnership to be registered with the “Registro Civil” maintained by the Ministry of Justice in Spain.” [Benidorm Hotmale]