BBC Two broadcast Dragon's Den before the programme moved to BBC One.
The British series began on BBC Two in January 2005 and remained associated with that channel for most of its early history. BBC Two was the BBC service traditionally known for factual, documentary and specialist programming, making it a natural home for a show combining entrepreneurship with entertainment.
The programme later transferred to BBC One in 2023. That move reflected its established popularity and gave the series a larger mainstream platform, but it did not change the central format: entrepreneurs still pitch for investment while the dragons assess the business and negotiate terms.
The channel history can be confused with the programme's filming history. Where the show was recorded, and which BBC channel transmitted it, are separate facts. BBC Two is the correct answer to the broadcasting question.