First, master J.M.D, you must understand about the stock market. Unlike commemorative coins from the mint today, where zillions are made, this rule does not always apply to Stocks. It depends on how much the company wants to issue i.e. How much capital to raise. So if they wanted to start a company and they needed £10,000 (hypothetically), they could issue two stocks of £5000, 10 stocks of £1000 etc. So it doesn't always apply that there are many certificates out there. Anyway, I wouldn't collect modern because they are revolting compared to the older ones.