Got it .... From the B&W catalog: "Filters Special Effects Acessories From the Pros to the Pros":

The filter is a B&W090 "Light Red" - equivalent to a Wratten 25 or Hoya R25.
The filter factor is given as 5 - requiring a filter correction of 2 1/4 stops- close enough to the 2 1/2 used.

All I can say is "That is what happens when a B&W090 is used to photograph roses".