I suspect the 18.5" Mira disc to which Jeff Adkins seeks the number
would be

  No. 106 -- Polonaise (from Mignon) (Thomas)

Members of MBSI can access their archives which includes, for early
1980, an archived magazine containing a nearly full list of Mira
titles, which have the same numbers and titles for both 15" and 18.5"
sizes.

Regards,
Nicholas Newble

 [ 12-year-old Julie Andrews sings the aria (very well, indeed)
 [ at http://www.youtube.com/watch?v=iV2-YGGn0y4
  -- Robbie