I've just read This Is How and was glad to read your review as it expressed some of my difficulties with the book. I found it a gripping read at first and then all the anachronisms and the inconsistencies really got to me and destroyed my enjoyment.
Does anyone out there understand why editors do not pull authors up about this? I gave up half way through A. S. Byatt's The Children's Book for the same reason. I emailed Byatt's publishers about it and didn't even get the courtesy of a reply.
I'm glad that a few online reviewers do actually mention these mistakes as most newspaper reviews seem to just praise any established author to the skies. I doubt if newpaper reviewers actually read the books with the attention "ordinary" readers do.