Apostille vs. Embassy legalisation for Sudan
Sudan has not joined the Hague Apostille Convention, so one British certificate does not settle a paper used there. Files heading that way need embassy or consular legalisation instead, which adds a desk behind the first. No apostille issued in Glasgow for use in Sudan is a finished job, and that has nothing to do with the quality of the sheet.
Sudan's Hague status & what it means
Membership of that treaty is a matter between countries, not between an office and an applicant. It is not weighed case by case, it is not affected by how strong your paperwork looks, and nobody handling your file had any part in setting it. Reading it as a personal setback leads to all the wrong moves.
What people do when they misread the wording
The common reaction is to go looking for a way around: a different certificate, a second opinion, a faster tier that somebody must surely offer. None of those exist here, and each costs days. The wording is not a door to be pushed at; it is a description of a road with two stages on it rather than one.
The useful reaction is duller and much cheaper. Start early, order the certified extract from Glasgow Registration Office at 45 John Street, Glasgow G1 1JE, and let the FCDO Legalisation Office at PO Box 6255, Milton Keynes MK10 1XX do the British act by post. Then hand the returned set to the consular stage and wait it out.
Cost & timing for this route
The British charge is £45 / document by standard post, or £40 / document next-day for a registered business, counted per document rather than per envelope, and an official charge falls due at the consular stage as well. An apostille from United Kingdom to Sudan is the smaller half of that bill and the shorter half of the wait.
Reading the corridor plainly
Two stages, two charges, one order of play, and no discretion anywhere in it. That is the honest description, and it is worth writing down for whoever is waiting at the other end. A reader who expects a longer road takes the extra weeks calmly; a reader promised a single stamp treats each stage as a setback.