Investors buy and sell shares through a stockbroker. Stockbrokers have to be approved by the UK financial regulator, the Financial Conduct Authority (or their home regulator if they are based outside the UK), and they need to pass certain specific exams, proving they are qualified for the job. There are hundreds of stockbroking firms and individual stockbrokers in the UK, many of whom are members of the London Stock Exchange. Investors can find these brokers, including local and specialised firms, using the London Stock Exchange website.
Different investors have different needs and stockbroking services fall into three broad categories, discretionary, advisory and execution only.