All I can find (assuming the original 'ECF' was some time ago,) are reports in modern 'classic' rallies.
It seems to be used these days to describe an entry that survives against the odds.(?)
http://www.hero.org.uk/lejog/awards.html
(Scroll down the awards, and have look-see at the Ecurie' entry. Is that what you mean?)
No? ...I'll keep looking.
