Hi,
I'm an alarm watch collector from Germany and have some (Jaeger) LeCoultre watches in my collection. I've got a quite untouched or slightly used Jumbo bumper automatic Memovox Cal. 815. The crowns are unsigned, but match the watch. The date of produce might be in the 1950th (1956 was the start of this watch). Another Memovox 814 has the "LeC" crowns and it is clearly dated with an inscription to 1.14.1962. A Memovox Parking with the 814 movement has unsigned crowns, too.
So do you know, when JLC has started to use signed crowns on their (alarm) watches?
I don't store pics at servers but have a couple of little video clips on youtube of my watches, so here is the link:
https://www.youtube.com/watch?v=9qMbHqsVJjE
Have a nice day!
Andreas