Which Dragon was the only woman on the original Dragon's Den panel?

Rachel Elnaugh was the only woman on the original Dragon's Den panel.

The first British panel consisted of five investors: Peter Jones, Duncan Bannatyne, Rachel Elnaugh, Simon Woodroffe and Doug Richard. Elnaugh therefore represented the sole female investor in the original line-up, before later panel changes brought other women into the den.

She was already known for co-founding Red Letter Days, an experience-gift company. Her presence gave the initial panel expertise from the consumer and leisure-gift sector, while the other original Dragons brought backgrounds in technology, property, hospitality and business investment.

This is a historical description of the first panel, not of the programme's entire run. Deborah Meaden later became a prominent Dragon, and other female investors subsequently joined as the cast changed. That is why identifying the original line-up is essential to answering the question accurately.