RIP Mike Pinder, he was pretty much the last surviving member of the group (Justin Hayward and John Lodge were not founding members of the Moodies, having replaced Denny Laine and Clint Warwick respecitvely after their 1965 debut The Magnificant Moodies.)
He was not only a Mellotron player, I think Mike Pinder also used a Chamberlin starting on the Seventh Sojourn album (an updated Mellotron which works on the same principle, made by the same company and, yes, sounds the same). That said, Mike Pinder was an excellent keyboard player for Moody Blues, he definitely introduced the Mellotron to a larger audience.