The betting booth could never have existed since, until 1960, off-course betting was illegal.
Shows Fitz getting mobbed by a Red Kite, yet in 1954 Red Kites in Englnd were practically non existent. Even as it was filmed in Scotland, the chances of seeing one there would be very rare indeed.
Lord Whitfield quotes a Bible verse to Fitzwilliam and says it is from Timothy chapter 4 verse 7. However, the Bible contains two books called Timothy, referred to as First and Second Timothy. The verse mentioned is from First Timothy.
The village bobby would have been wearing the traditional domed helmet, rather than the peaked cap which was for patrol-car officers and higher ranks. Also it is likely he would have worn the old-fashioned tunic buttoned up to the neck as opposed to the open-lapel version.
The Racing Post wasn't launched until 1986, long after the events in this series. The book was written in 1939 and the environment portrayed seems similar to that era.