Mellotronists

I heard Led Zep this morning-All of my Love and wanted to know if the  string 
section that was recorded was a Mellotron or one of the many String  synths 
used during that era. Also, to what extent was the Mellotron  used during Led 
Zep recording career?
                                                                              
   Jimmy Moore
                                                                              
#285; and awaiting  F/X 006