SCW Civil Guards uniform-which one to choose?

[OB]

I'm about to start painting a unit of Spanish Civil War Civil Guards and I'm looking for advice. 

I've seen these outfitted in blue or in military green green.  The blue is, I think, their pre-war uniform.   The green was issued, I guess, during the war. 

Was there a formal change of uniform or did both continue to be worn?

Thanks in advance for any help.

[SJWi]

OB, Bob Cordery's book La Ultima Cruzada and the Osprey MAA both only refer to the grey-green service dress for the Guardia Civil. The Guardia de Asalto did wear blue.

[OB]

Thanks very much SJWi.  I'll go with grey-green then.  I'm glad I asked before painting.  Appreciated!