The signature that carries the document
One signature does the real work. A certified translation of a Translator's Affidavit in Bristol is carried by the translator's own hand, not by yours and not by any office. The declaration names both languages, states that nothing was dropped or added, and gives the translator's credential. It is bound to the pages it describes, so a reader can see at a glance which text was sworn.
The person who watches it happen
Next comes the witness. Because this is a private act, a solicitor or a notary public has to be present when the translator signs. They take proof of identity, watch the pen move, and add a seal with the date. The witness is not asked to read the target language, and there is no rule that they must practise in Bristol.
What the seal is worth
The seal is narrow on purpose. It proves that a named and identified person signed this page on this day in front of the witness. It says nothing about how good the translation is, because that is the translator's oath to give. The pair together is what a receiving desk treats as an official translation of a Translator's Affidavit in Bristol.
The source record, and how the country reads it
If the sworn text rests on a civil record, order a fresh copy first. Bristol Register Office at The Old Council House, Corn Street, Bristol BS1 1JG issues certified copies of births, marriages and deaths registered in the city, so your own certificate can stay put. From there the rule is national: a certified translation of a Translator's Affidavit in United Kingdom practice is the translator's sworn accuracy statement, witnessed and sealed.