Rough Guide has updated its guidebook "Walks in & Around London" and it will be released in mid-September of 2023. One of the nice things about Rough Guides (other than that is a very good guide book) is that if you buy the physical (paperback) book, you can also get a free download of the eBook, which will be very handy when you're out walking around in London!
UPDATE: As Frank II noted below, you can now open EPUB books on Kindle. Just follow the link he gives below. Very easy!
You can also open it in other book mediums such as Apple Books, Google Play and Adobe Digital eReader. https://www.amazon.com/Rough-Around-London-Travel-Guides/dp/1839058498/ref=tmm_pap_swatch_0?_encoding=UTF8&qid=&sr=
It's perfect timing for me so I will definitely be ordering it.
ETA: I just took a peek at the Table of Contents and it also includes lots of walks outside London, like around Oxford, Blenheim, Kent, Sussex, Cambridge, the Fens and so on.