Who was the first female investor to join the regular panel of the UK show Dragon's Den?

Rachel Elnaugh was the first female investor to join the regular panel of the UK show Dragon's Den.

Elnaugh was an original dragon when the BBC series began in 2005. She was known as an entrepreneur in the retail and business sectors and brought experience from building Red Letter Days, a company selling experience gifts.

Her tenure belongs to the programme's early series, before later female dragons including Deborah Meaden, Kelly Hoppen and Sara Davies became familiar to viewers. The panel's membership has therefore changed substantially since the first season.

This question is about the first regular female panel member, not the most successful female investor or the first woman to appear as a guest. Rachel Elnaugh is the name associated with that original-panel distinction.