Montgolfier brothers

The Montgolfier brothers were French brothers who invented a kind of hot air balloon. When the Eighth Doctor brought Christian and Madeline de Roche into his TARDIS, he claimed it was a hot air balloon made from a design by the Montgolfier brothers. Madame De Roche was excited by the revelation because the Montgolfiers were French like herself. (AUDIO: Other Lives)

Behind the scenes
The brothers were referenced in the Doctor Who Annual 1977 feature The Airship Rises to Fame, which explained that they invented the first ever hot air balloon in 1784.