Morris Minor Owners Club

I am treating the woodwork on Horace and have poured preservative into the drain holes on the mid rail. The rear drain hole has spilt it's contents into the car via a cut out section for something or other. Presumably they are supposed to be separate and rot has bridged the gap.Ideas how I can stop water coming in would be appreciated.
Ta

It's supposed to run out through the drain holes - make sure they aren't blocked when you finish soaking it all in preservative. I temporarily blocked the drains and flooded the runners.

Did it run in near the back? A big screw goes into the rear post at an angle and its quite close to a drain hole, chances are its rotted through there. On my traveller a few years ago I used a "wet rot hardner" which is some sort of liquid that soaks into the wood fibre and hardens it, then some wood filler to stop the water getting in. It worked ok for a couple of years until I replaced the middle rail.