1 INTRODUCTION  
1.1 Why CLAGN change spectral type  
1.2 Known CLAGNs  
2 CANDIDATE SELECTION  
2.1 Imaging surveys and catalogues  
2.2 Optical colour selection  
2.3 Optical flux variability selection  
2.4 Infrared flux variability selection  
2.5 AGNs with 2 or more archival spectra  
3 SPECTROSCOPIC FOLLOW-UP  
4 SPECTRAL VARIABILITY AND NEW CLAGNS  
5 CONCLUSIONS