As I left it last night.
I added this next photo to this post on the 29th July. The white part of the socket is a $2.50 plumbing fitting cut to size and glued on so that is extends about 3mm past the end of the extension cord's socket. Since the Vogue's plug is elevated above the "moat" by the same amount, it forms a splashproof connection. You can see the drain hole which goes via a plastic hose in the boot (the original) down through to under the car. I have now charged several time in pouring rain with no water at all getting under the socket.
That's not my 150K Ohm resistor - it's in the original sealed socket! The socket has a pathetic little red LED that is barely visible when the power is on.