So, Davina McCall is a very famous TV presenter in the UK. She presented the first few series of Big Brother, and had a brief cameo in the Doctor Who episode Bad Wolf as the presenter of Big Brother In Space.

She currently presents a programme called Long Lost Family, where they try to find people's... long lost family members. Which is what her appearance is referencing. However, Long Lost Family is on ITV, while Doctor Who is made by the BBC.

I clipped out her cameo around the same time I wrote this. Here she is