Apostille vs. Embassy legalisation for Kenya
British papers going abroad end their certifying life in one of two ways. Either a single certificate is added and Convention countries read it on sight, or the file keeps moving until a foreign desk has stamped it too. The receiving country picks the ending, never the sender and never the office holding the pen. Document legalisation for Kenya follows the longer of those two endings.
Kenya's Hague status & what it means
Kenya has not joined the Hague Apostille Convention. In practice that means an apostille issued in Derby for use in Kenya is not accepted there on its own; it is a first mark, and a Kenyan consular desk later stamps on top of it. Read the British certificate as one stage of an apostille from United Kingdom to Kenya rather than as the product itself, and a lot of confusing advice suddenly sorts itself out — most of it was written for destinations that finish sooner.
The Derby → Kenya route step by step
Your own choices all sit at the Derby end. Certified copies of local civil entries come from Derby Register Office at Riverside Chambers, Full Street, Derby DE1 3AF, which is how a spare version of the record enters the chain in place of the one you keep. The British mark then comes from the FCDO Legalisation Office, PO Box 6255, Milton Keynes MK10 1XX, by post. After that a Kenyan consular desk closes the file under rules of its own making.
Cost & timing for this route
The British side publishes its price: £45 a document by standard post, or £40 a document next-day where the sender is a registered business. Since the charge lands on each document, a spare copy is a second charge and a second set of postal legs. And because a finished bundle cannot be turned toward another country, buying the number of sets you actually need at the outset beats discovering afterwards that the one you have points the wrong way.
Destination-specific requirements
Everything here is shaped by one decision: which country reads the paper at the end. Convention routes are forgiving about that, because a British certificate finished for one such country looks the same as one finished for another. This corridor is not forgiving, since the closing stamp belongs to a single government. So what you need for an apostille for Kenya starts with naming the country before a penny is spent, rather than after the envelope has gone.