The Court Circular is a document that is issued daily during the week, except for public holidays to selected newspapers, including The Times AND is usually put up on the British Monarchy website.
The reason people have to refer to the version in The Times is that the online one, last year in particular, was so unreliable e.g. it never put up Trooping the Colour as an official event - didn't put up the entire day - but that day was in the print media where it has been since George III introduced the idea in the first place.
The 'official' count that is published each year is done by a man who uses The Times and has done so since the early 80s. He doesn't rely on the online CC which is just so hit and miss at times ... although so far this year it has been reasonably good, even putting up dates later that were originally missed (were in The Times on time but not put up until called out by this and other sites for the missing days).