English is what Jamaica requires
A certified translation into English in Sheffield is what Jamaica requires for a document that is not already in English. State that plainly and the rest of the route falls into place. The English text is written from a scan, signed and dated, and it travels with the source page rather than replacing it.
The language on the page, not the country you live in
People work this out backwards. They ask whether a document from Britain needs translating for Jamaica, when the real question is what language the document is written in. Plenty of people in Sheffield hold records issued in Warsaw, Lisbon, Bucharest or Mogadishu, and those pages need an English version before anyone in Jamaica can act on them.
So the test is short. Pick up each paper in the file and read the top line. If it is English, the language step is done and nothing needs writing. If it is not, that page needs an English text beside it, signed by someone who is answerable for the match between the two.
The pairing is what you are buying
A translator is qualified in a pair of languages, not in translation as a general craft. Someone who works from Polish into English is not thereby able to work from Amharic, and the certificate of accuracy is only worth something because a named person with that specific pairing put their name to it. Send the scans early and the right pairing is found before the clock starts.
One practical result: everything hard on the source page is copied rather than composed. Names keep their spelling, dates keep their values, and reference strings are reproduced character by character. The English carries the meaning, and the values underneath stay identical so a reader can hold the two pages together and see that they belong to each other.
Cost and timing
Pricing is £25 a page and the count is taken from the scan, so the size of the job is settled before anyone writes a line. Standard work takes 2–3 business days; the express route closes in 24 hours. Both give you the same signed English set, and speed changes the place in the queue rather than the standard of the work.