Once the lease of a property gets to below 70 years, it becomes very hard to secure a mortgage on it. I sold my flat in London when the lease was just 71 years, and I was so worried that the purchaser's solicitor would bring up the question of a lease extension.....but they never did.
Now, over 11 years on and with the lease on that flat below 60 years it is unsaleable other than to a 'cash' buyer. Glad I got out and bought a freehold!
Make sure you use a solicitor who is au fait with leases - they can be very tricky.