[78-L] LP set. Need date.

[jack palmer]

I know this if outside the 78 L field but I know all these songs were probably recorded more than once on 78s.  
    I have a boxed set of 3 LPs in stereo titled THE BEST OF GILBERT AND SULLIVAN.  The number shown is 3 CSL 1008 1 AND 2 AND 3.  The numbers are the same except the last number on each record.  The records look brand new and a 300 page hardback book is included.  As a G&S fan I am impressed.    
     Does anyone know when this set was recorded and issued?  The book is shown as copyrighted in 1976 but the recordings could be earlier.   Thanks.   Jack