British group launches hybrid rocket to 25,000 feet.
according to this BBC article. However, it appears the article has some errors. For example, it says:
"The rocket is groundbreaking in many respects being the largest rocket ever built in the UK, including military rockets. It is also the most powerful UK-built hybrid rocket motor ever."
It may well be the largest British hybrid rocket ever built but certain isn't the largest British rocket of any kind. Here are but a few counter examples:
Black Knight sounding rockets.
Black Arrow launch vehicle.
Blue Streak IRBM, also used as the first stage of the Europa launch vehicle.