Hello
I am sorry to say this car is in a very bad state.
I would say the rain gutter at the side of the windscreen has been
leaking due to shrinkage of the sealant.
Water has been coming inside the hollow section and running down
inside the A post into the carpets.
The carpets must have been wet for several years.
The car is going to need substantial repairs to the inner sill, floor
pans, jacking point and A post.
I would suggest welding a brace across the door aperture before
cutting any more to retain the integrity of the structure.
I would say this is a job for someone who has worked on Stag inner
sills before.
It is rare for so much rust damage at the front end. they usually rot
out at the rear end which is an easier repair.
When I undertook a survey amongst 7 professional repairers about
repairing or replacing complete inner sills, only 50% of the
professionals out there were happy to replace complete sills. The
other 50% would prefer to repair them as they wanted to remove as
little of the good metal as possible.
The replacement inner sills on the market today are made in metric
steel and it is very slightly thinner than original Imperial steel so
skills in terms of assessment. welding and repair design are paramount.
At the risk of being branded a complete party pooper, I would say this
car needs to be very good elsewhere to be worth repairing as it is
looking very expensive from what I can see.
PeterH