Left side: the dark panel to the left is the inside of the front/left wheel arch. To the right is the front edge of the left front door. We still have the jacking point, but the sill above it has been cut.
If you open a front door, there is a little triangular water catching bassin just above the upper hinge. The bassin has a drain hole, with a pipe that almost horizontally goes through the front door post. Then, in the engine compartment, a hose is attached to the pipe to bring the water down and out. Well, sometimes that last "out" is clogged, or the hose is not like new anymore.

You better check this place! It is in the engine bay, behind the wheel arch and down. On RHD cars it is more or less hidden behind the battery; even if you take the battery out, you'll need a mirror and a lamp to inspect it. Obviously there is an equivalent place on the other side, that's even more difficult to inspect since it is hidden behind the master brake cylinder (which cannot be taken out as easily as the battery can).