The two former official measures of social class - Social Class by Occupation (SC), previously known as Registrar General's Social Class (RGSC), and Socio-economic Groups (SEG) - were discontinued in 2001 when the National Statistics Socio-economic Classification (NS-SEC) was adopted as the sole official measure of social class in the UK. Derivation Matrices for the Former Official Measures of Social Class, 2000, 2010 and 2020 provides derivation matrices for SC and SEG from the Standard Occupational Classifications 2000, 2010, and 2020 after their official discontinuation to enable their use in longitudinal data and comparative analyses.Further information is available in the publications detailing the 2010 and 2020 work. Derivation matrices for SC and SEG are available from the Standard Occupational Classifications for  2000, 2010, and 2020. These derivation matrices can be used on any data with the relevant occupational data.