"The quote is recorded as being from a 1839 Wellington conversation, is it not?"
Right, the 70-year-old Wellington recalling what had been said 26 years earlier. I was asking about the publication of Stanhope's work. I did not find it published before 1886. By then there would be no likely survivors among those who either heard the remark or heard of the incident. I was quessing that maybe Stanhope had also been published earlier.

But you have clearly found the right solution, the incident is perfectly reported and the Parisian officer was noting that while the British formed an army, the French were nothing but a small closed hackney coach appropriate to private trysts.

So witty those Parisians ! I would never think to describe an army as a "livery cab".

My wife loves Brel. Also Serge Gainsbourg and Jane Birkin. [rolls eyes]

Natalie Dessay is more my speed. The aria from the cantata "Ich habe genug" on her website is a good example of her style.
http://www.natalie-dessay.com/