Is there a legal requirement for x number of crew to x number of pax?

I did this run once and was "upgraded" to the F cabin when they decided to open it to accomodate the loads. But the service was very below standard. It appeared they only had onboard crew for the Y/W/J cabins but were having to service pax in the F cabin too. All I got for breakfast was a dried out bacon roll thrust at me. No breakfast tray or anything! Was really very poor.