Yes, Steve. Despite my readiness to accept the "thumbs-up" solution on Jan. 5, I must admit now that it won't quite do.

The two-finger sign isn't impossible, but the seemingly inseparable "slang phrase" remains a mystery. I'm unaware also of any use of the victory V in World War I.

And at least in Brophy's experience, the gesture-and-phrase combination was common.

If any 1914-18 victory V's can be found, that might solve half the problem.

Meanwhile, Wikipedia has a useful article on the Roman gesture. (It wasn't as most people think.)

https://en.wikipedia.org/wiki/Pollice_verso