Britain's House of Lords last week passed the Civil Partnership Bill by 251 votes to 136.
New Zealand's Parliament is awaiting a select committee report back on the Civil Union Bill and its accompanying Relationships (Statutory References) Bill.
The first recognises both same-sex and heterosexual de facto relationships using wording which parallels the Marriage Act, while the latter deals with legal next-of-kin issues which at present are confined to spouse, or husband and wife.
The report back will be tabled next Monday and Parliament is expected to go into urgency before Christmas to pass the legislation.
"The great show of confidence by British parliamentarians in this legislation is a clear signal that the proposed legislation in this country is right in step with international norms," Mr Fairbrother said in a statement.
An increasing number of western democracies now recognised same-sex relationships, including France, Germany, Hungary and Denmark, he said.
"This widespread international support for recognition of same-sex relationships through some form of civil union legislation is reflected in opinion polls in New Zealand, which have consistently shown that the introduction of civil union legislation is widely supported here."
