Cliff Stanford, one of Britain's Internet pioneers, has been charged under the Regulation of Investigatory Powers (RIP) Act 2000 with conspiracy to blackmail and the illegal interception of communications.
Stanford, who was arrested by officers of the National High-Tech Crime Unit and charged on Thursday, is accused of illegally intercepting the emails of John Porter, chairman of Internet company Redbus. A second man, George Liddell, was charged with the same offences last month.
Stanford, who founded both Redbus and Demon Internet, is reported to have denied both charges. He and Liddell, described in reports as a corporate troubleshooter, are due to appear in court next month.
Police began investigating Stanford last year after he resigned from Redbus and sold all his shares in the firm. It is understood that the charges against him relate to allegations that he secretly intercepted emails sent to John Porter from his mother, Tesco heiress and disgraced former politician Dame Shirley Porter.
Dame Porter was a key player in the "homes for votes" scandal of the 1980s, under which council homes in Westminster were sold to potential Conservative party voters. She was hit by a surcharge of £37m after an inquiry into the affair, but insisted that she couldn't produce so much money, and only had assets worth £300,000 to her name.
Reports have claimed that in the allegedly intercepted emails Dame Porter referred to millions of pounds being available to her son.
Stanford and Liddell have been charged under Section 1, subsection 1 of the RIP Act. This states: "It shall be an offence for a person intentionally and without lawful authority to intercept, at any place in the United Kingdom, any communication in the course of its transmission by means of (a) a public postal service; or (b) a public telecommunication system."
If convicted, both Stanford and Liddell could be fined or jailed for up to two years. They are due to appear at Bow Street Magistrates Court on 2 March.