In case of buyback of shares purchased before 31-01-2018, is Grandfathering of Long Term Capital Gains allowed?
Yes, due to the following reasoning:
Grandfathering under Section 112A applies to any transfer of listed equity shares where STT is paid on purchase and sale.
A buyback under Section 68 is legally treated as a transfer by the shareholder. You are “selling” your shares back to the company - just not on the exchange.