The signature at the foot of the page
Document legalisation for Ethiopia is usually described as a sequence of offices, which makes it sound as though everyone starts in the same place. They do not. The starting point is set by whoever signed your sheet, so two people in the same street with two different papers begin their runs at two different desks.
Where Ethiopia stands
Ethiopia has not joined the Hague Apostille Convention, so the single-certificate shortcut is not on offer for this corridor. There is no apostille issued in Reading for use in Ethiopia that ends the job. The older route applies: a British certification stage, then a consular stamp obtained for the receiving country.
Two starting points people mix up
Civil records are the easy case, because the register office can reissue them and the sheet that travels is one you can replace. Everything else is harder, since the issuing body may sign in a form the British stage does not recognise. An apostille from the United Kingdom to Ethiopia would not rescue a sheet in the wrong shape either.
What the middle stage charges
The British certification is priced per document, at £45 for the standard postal service, and that charge covers that office and nothing beyond it. Since it repeats for each sheet, the first stop is where the money is decided too: a paper obtained in the wrong form and sent twice is charged twice.
Reading the route backwards once
What you need for an apostille for Ethiopia is, in practice, a list of first stops rather than one address. Write down each paper, name the body that issued it beside it, and only then work forward. Ten minutes with that list is worth more than any amount of speed later in the chain.