Always wondered about that picture. It is usually interpreted as an old soldier thrusting his cap under King George’s nose in search of money, though it could just as easily be interpreted as an old soldier running alongside the King’s carriage with his hat off in respect. It’s all about the frame and how one interprets it. Can’t find a film of that moment, alas.
Below is Pathe coverage of the 1920 Derby. You can see that there was considerable police presence- though oddly not around the King in the picture, begging was common- though people from ‘lower classes’ also seem to ignore the woman with child, and the crowd was fascinated by a presumably African speaker. If only there were volume. :-(
As for Mogg’s list, it seems to include personal preferences rather than rules that grammarians might recognise.