Capital Gains Tax on overseas share sales. Can I claim First in First Out Price?

Whilst living abroad and being tax resident overseas, I purchased a number of shares in a company I worked for over a period of 20 years. I am now a UK tax resident and considering selling some of those shares. My main purchase was 20 years ago when I purchased 10,000 shares at 45 US Dollars per share. Since then, there have been 22 purchases and 4 sales. I now own 22,334 shares. The stock is trading today at 36 US Dollars. I have made no purchases or sales since returning to the UK 8 years ago. If I sell 5,000 shares at 36 US Dollars, can I claim a purchase price of 45 US Dollars?

Hi,
If they are all in the same company this would be treated as a S104 holding. please refer to:
Shares and Capital Gains Tax (Self Assessment helpsheet HS284)
Thankyou.