Which Dragons' Den investor founded the retail group Phones 4u?

John Caudwell founded the retail group Phones 4u.

Caudwell and his brother Brian built a major mobile-phone retail business in the United Kingdom during the rapid expansion of consumer mobile telephony. Phones 4u became a familiar high-street name, selling handsets and contracts from multiple network providers rather than operating as a single network itself.

John Caudwell appeared as a guest dragon on Dragons' Den rather than becoming one of the programme's permanent regular investors. That distinction is important: the television series has featured guest investors alongside its established panel, and guest appearances can be mistaken for full-time appointments.

The business is commonly written as “Phones 4u,” with the numeral in the brand name. Caudwell later became known for philanthropy as well as entrepreneurship, particularly through the Caudwell Children charity.