Subject to subsection (2) and sections 142A, 143A and 143B, where—
a secure tenant has claimed to exercise the right to buy, and
his right to buy has been established and his notice claiming to exercise it remains in force,
he also has the right to acquire on rent to mortgage terms in accordance with the following provisions of this Part.
The right to acquire on rent to mortgage terms cannot be exercised if the exercise of the right to buy is precluded by section 121 (circumstances in which right to buy cannot be exercised).
Where the right to buy belongs to two or more persons jointly, the right to acquire on rent to mortgage terms also belongs to them jointly.