Investing £10,000 in Barclays shares during the March 2020 lockdown could have yielded significant returns, with an approximate 200% gain, increasing the investment to £30,000, plus £1,800 in dividends. While Barclays shows potential for value and earnings growth, risks remain due to market volatility and macroeconomic uncertainties. Investors should carefully assess these factors against their risk tolerance and investment goals.