Robert Neill was a very careful recorder of historical events, For all his books he spent time in the area and checked dates and events very carefully. For some years he actually lived in Cheltenham, the scene of the big events of "The Shocking Miss Anstey."
He did howver make (at least) one mistake of fact in Anstey, one which with his naval experience he should never have made."
In Chapter 25, as Richard and Mary were walking homewards in the evening he wrote:
"Half past ten, late for Cheltenham, .... a crescent moon rose above the hills".
The moon of course always rises in the east, and moonrise at such a time in the evening, when the moon is on the opposite side of earth to the sun, is necessarily an almost full moon, not a crescent. 4:00 or 5:00 in the morning is when you can see the rising of a cresent moon, in the east.
You can see a cresent new moon in the evening in the west, but it is setting, not rising.
Living where I do, with the moon always part of normal daily life, this struck me immediately as obviously wrong. For those living in cloudy England, the moon might not be quite so obvious. But Neil specifically mentions it along with all his comments about Richard's close observations of the skies.