Which papers actually need translating
New Zealand handles official business in English, so a British record usually needs nothing. The files that do need work are the ones issued elsewhere and now sitting in a drawer in Wolverhampton: a Polish birth entry, a Filipino marriage record, an Indian degree, a police certificate from a country you once lived in.
English, and the completeness that reviewers look for
A certified translation into English in Wolverhampton reproduces the entire page rather than the useful-looking parts. Seal wording, revenue stamps, endorsement notes and reference numbers all appear. Reviewers work through a checklist, and a missing endorsement on a police certificate reads as an incomplete document even where the substance was perfectly fine.
The certificate that makes it official
The route here is a certified translation with certificate of accuracy, signed by a certified translator. The certificate is a page in its own right, giving the translator's name, the direction of the work, the date and a statement that nothing was added or dropped. It is what turns a good English text into a certified translation for New Zealand.
Rate per page and the delivery clock
The rate is roughly £25 / page of source, and the count comes from what you send rather than what comes back. Standard work takes 2–3 business days, and express work is done in 24 hours. Because applications are usually assembled over months and filed in a rush, most people order the whole set at once near the end.
Fresh UK records, and what a reviewer checks
Where a UK civil record belongs in the file, Wolverhampton Register Office at Civic Centre, St Peter's Square, Wolverhampton WV1 1RU issues new certified copies of births, marriages and deaths. The fresh copy is the one to part with, keeping your own record safely at home. That office issues records and has no role in translating them.
A New Zealand reviewer opens the certificate, counts the pages against it and then matches names to a passport. An official English translation in Wolverhampton is accepted on being complete, independent and signed. What sinks a file is a page left out or a name that appears in two forms with nothing sent to connect them.