Yes, individual retail investors can purchase shares in Celtic Football Club because the parent entity, Celtic plc, is a publicly traded company listed on the Alternative Investment Market (AIM) of the London Stock Exchange under the ticker symbol CCP. To buy shares, an investor must open a standard share-dealing account with a registered online or offline stockbroker that provides access to the London Stock Exchange. Once the brokerage account is funded, users can search for the "CCP" ticker symbol and execute buy orders during standard market trading hours.