I ought to have read this when I was younger and I'd certainly recommend it to young readers interested in remembering trivia, dates and scientific factoids.
At my age there's just too much stuff in here for me that wasn't new but what struck me was how dated some of the style was. Mnemonics can be fascinating and handy but they work best when related to the topic.
"Dashing in a rush, running hard or else accident" is a great way to remember how to spell diarrhoea. It's linked to the topic and funny (but not in this book) and therefore more memorable. Too many of the mnemonics in this book are random phrases, which aren't necessarily the easiest things to remember in themselves. Chris Stevens has done a fine job in compiling all of this information but I'd have appreciated some effort in updating it too.
"No Point Letting Your Trousers Slip Half Way" is intended to help us remember the English Royal Houses (Norman, Plantagenet, Lancaster, York, Tudor, Stuart, Hanover and Windsor) but has no bearing on the topic. That's not to say it can't be remembered but why not try to overhaul it? `Noble posh leaders, yet they're still half-wits" would do the job (if inaccurate and defamatory) or "No peasant loves your throne, so hear wisdom".
I'm a grump and I'll admit it. I remember "Never Eat Shredded Wheat" for North East South West and "Richard of York Gave Battle In Vain" for the colours of the rainbow (with the added advantage of including trivia about the last of the reigning Plantagenets) and these mnemonics have no relationship with their subjects. Perhaps then I'm being overly critical. Nonetheless, some of this stuff could definitely be improved upon.
Still, good for kids with some fun rhymes. I think it would work best alongside some other kind of memory teaching if you're hoping to absorb the information. Not a work for someone trying to actually improve their memory.