Value of Older Rolls Royce Shares for CGT purposes

I have purchased Rolls Royce shares over a 20 years of previous employment. At the time of purchase thise shares predominantly had a higher purchase value than the current share price. In 2020 RR did a rites issue and valued existing shares at 33p. Employees could use a process called tailless purchase where some share were sold Al others retained. I will still use my original share certificates so do they retain the original purchase value or is the loss taken at 2020 able to be rolled to now? I need to know how if I will owe CGT?

Hi,
Please refer to guidance at HS285 Share reorganisations, company takeovers and Capital Gains Tax (2024)
Thank you.