There are two leases - a 99 year lease and a 999 year lease. I have a copy of the 99 year lease.
The 99 year lease is the underlease - the one assigned to me from the previous owner but I know I bought the flat because of the 999 year term.
Maybe I am confused. I think there is a 99 year lease (called the headlease) from 30th September 1972 between the Greater London Council and Lancaster Gate Housing Association Limited. Then there is a lease between Lancaster Gate Freehold Limited and the Leasee which is me but I am trying to find the 999 year term in the documents. Sorry.