This was greater fun than I thought it might be. Its a very pleasant way to pass a couple of hours with your brain largely in ‘rest’ mode. The initial idea is actually more fun than I first thought it would be and Millie Bobbie Brown makes a very appealing heroine - not nearly as infuriatingly perky as such characters often are - and even the occasional remarks to the viewer were not the irritating trope that I feared they would be. Helen B-C is excellent as the very liberated mother while Henry Cavilll is a very decent Holmes
The plot is decently complicated with a number of strands and false leads but it all ties together nicely. And there is the usual smart of at times slightly predictable mixture of personal drama, life and loves, and contemporary political events - where the main characters are, of course, always on the side of the angels - in this case the Great Reform Bill
Visually it is excellent; the English countryside has never looked more archetypally summery while London, thanks to CGI I assume is impressive although with that glossy smoothness that seems to be a characteristic of such modern creations.
So, good clean fun - and I suspect the sequel will be equally effective.