I thought I'd posted on MN about this issue, but I can't find it in my feed, so I'll summarise it as best I can.
We have LPA for my mother, who is now living in a care home, she's mid 90's.
This is the second winter her house has been empty, so we're selling it.
Accepted an offer in Oct and all was going well until the middle of Nov when the buyer's solicitor discovered an unregistered lease from 1935 running for 99 years.
My parents bought the freehold in 1991.
Panic stations all around, especially for us.
Solicitors have been great.
It went to the land registry in the last four weeks & just found out today we've been successful and the lease has now been registered and we can go ahead with the sale as a house with freehold absolute.
The solicitor said in her experience it's 50/50 if the land registry register the lease, many are unsuccessful.
We've been successful and it's an almighty weight off our mind.
It is quite rare, but for anyone who is going through this scenario....it can be done.