Yes, just a sales slogan thought up before trades descriptions and not to be believed literally...
Like...
DOT motorcycles.. (Devoid of Trouble)
SOS..(So Obviously Superior)
BAT Motorcycles..(Best after Test)..etc. etc.
and not forgetting the 'Unapproachable Norton'...
...Ian
email (option): ian@wright52.plus.com
I think a lot of these slogans had their origins way back before WW2, many probably originating in the 1920's era when there were a proliferation of manufacturers all eagerly competing for a slice of the market against the increasing presence of the car..........
James in particular produced some rather nice 4-strokes during this period, before their fortunes saw them standardise on proprietary Villiers 2-stroke engines before the war for the cheap and popular commuter market.........indeed, apart from a few bicycles and autocycles their wartime production efforts were largely for armaments, instrument and aircraft components........I would suggest that upon receiving the comparatively miniscule order mid-war for the supply of motorcycles again (the ML) the company were justly pleased and in their advertising harked back to profitable earlier times in the face of numerous machines from BSA, Norton, etc.......although ironically there was little comparison between the mundane ML and the company's premier 4 strokes of earlier years
I think by famous James more on Scotsh Whiskey
And probely it was there before the 4 stroke 
Regards
Bram
email (option): bram@ockhuizen.com