Shares were once touted, sometimes from door to door, by share pushers who made unsubstantiated statements regarding the shares. The matter was dealt with by the Prevention of Fraud (Investments) Act 1939. Now no one can deal in shares without a licence, except for members of the Stock Exchange, etc. Misleading statements, etc., may be an offence, and circulars inviting persons to purchase shares must comply with the provisions of the Companies Act 1985, i.e. they must take the form of a prospectus.
Reference: The Penguin Business Dictionary, 3rd edt.