Sorry George, I don't want to gang up on you as such, but I'm absolutely certain that a drip tray is a necessity for classic bikes, far more so than modern ones for obvious reasons.

The picture you've linked to is of Sammy Miller on a 500 Gilera, presumably restored by him to period accuracy. It is also, quite obviously, taken in a parade.

Regardless of that, modern bikes have been dropping plenty of oil lately. Ryan at the NW200 for example. Not going to name any names about who told me but I was told this was due to the oil level sighting glasses blowing out of the crankcases - which is why in many cases competitors were continuing for some time, unaware of a problem.