Finally got round to the driver's side sill today.
Not good....it's crusty around the jacking point as usual but also found a stretch of about 2 ft on the flat bottom from the jacking point going towards the front.
It's not too bad but the underseal was hiding it.
Out with the angle grinder to remove the underseal and after about 5 minutes....bang.
One piece near me noggin and the other was about 15ft away.