Helen Sharman became only the 12th woman to fly into space when she took part in the flight in the Soyuz TM12 spacecraft which blasted off from Kazakhstan, Xinhua reported.
Her two fellow crewmates were Russian cosmonauts Anatoly Artsebarsky and Sergei Krikalev and their flight docked with the Mir space station on May 20, 1991.
The team spent six days on the orbiting space station, carrying out scientific experiments.
All three were reunited on Friday at London's Science Museum.
Sharman, who was chosen for the flight from among 13,000 applicants, is now the operations manager in the Department of Chemistry at Imperial College, a leading science university in London.
Krikalev is a veteran astronaut, having spent 803 days in total in space, the second highest total for any human.