off of - as in "Whoever got the note off of Hammersely" (Kate Moore) 'off of' is a peculiarly American English grammar construct and unlikely to be found in the mouth of an English person.

royal army - "....Lord O.....y had just purchased his commission in the royal army...." While the maritime arm of the UK's armed forces is known as The Royal Navy (having been started as a permanent institution and funded by Henry VIII, and known then as the Navy Royal), the land forces do not bear this suffix. The phrase 'royal army' would only be used to differentiate it from another type of army e.g. a republican army. 

sash windows - I have recently read a short story, in which "... the wind simply blew the sash (Marcus' note: window) open and the crashing sound we heard downstairs was simply the window frame blowing back against the wall." THIS IS IMPOSSIBLE. Sash windows consist of two windows that slide up and down within the window frame. Sash windows do NOT open outwards or inwards.

Scepticemia - a rare but prime example of the care needed when using medical terms. OK to use in descriptive text but not in conversation as  'scepticemia' was not coined until 1837 by the French physician Pierre-Adolphe Piorry (1794-1879)

sidewalks - commonly found carpet tack

pavements in Regency London and all provincial cities of note - Bath, Brighton, Cheltenham, etc.

Stir crazy - was first recognised as a two word phrase - some 90 years after the end of the Regency period - in 1908.