A Silver Jubilee
is a celebration held to mark a 25th anniversary.
In the United Kingdom, a Silver Jubilee is held in a monarch's 25th year (followed by a Golden Jubilee after 50 years). Queen Victoria celebrated the jubilee in 1862, King George V in 1935, and Queen Elizabeth II's silver jubilee was in 1977.
Various things were named after the 1977 Jubilee, including the Jubilee Line, and Derby was granted city status. It is also notable for the the Sex Pistols release God Save the Queen.