Based on the facts stated by you, the answer primarily depends upon the terms of the registered lease deed. As a general rule under the Transfer of Property Act, 1882, a lessee may transfer or sub-lease his interest in the leased property unless there is a contract to the contrary. Therefore, if the lease deed neither expressly permits nor expressly prohibits sub-leasing, the trust may, in principle, create a sub-lease of its leasehold interest.
However, the trust cannot confer greater rights than it itself possesses. Since only 10 years of the original lease period remain, the trust cannot legally grant a sub-lease for 50 years. The doctrine of nemo dat quod non habet (no one can transfer a better title than he himself has) applies. Any sub-lease created by the trust can ordinarily operate only for the balance period of the head lease, i.e., the remaining 10 years, unless the original lessor separately agrees to extend or renew the lease.
Accordingly, even if a document purporting to grant a 50-year sub-lease is executed, the sub-lessee cannot acquire rights beyond the subsistence of the original lease. Upon expiry or lawful termination of the head lease, the sub-lease ordinarily comes to an end unless the owner has independently recognized or entered into a fresh arrangement with the sub-lessee.
Further, since the lessee is an educational trust, you should also examine:
- Whether the lease restricts the use of the land exclusively for educational purposes.
- Whether the trust deed authorizes leasing or sub-leasing.
- Whether any permissions under applicable laws or regulations governing educational institutions are required.
Therefore, on the facts stated by you, the trust cannot validly grant a sub-lease for 50 years when only 10 years of the original lease remain. At best, subject to the terms of the lease deed and absence of any prohibition, it may grant a sub-lease only for the unexpired portion of its own leasehold interest