Just a  another comment .
The  original screend bottom Boards has been in my use since May or June
1999 and  the second version immediately  after Apimondia  in Vancouver
BC / Ca  in Sept 99. Prior to these dates another  design for the same
purpose  is / was  explained  at a French  web site . According to  other
reliable sources  reports the  use of and the  results of the use were  5
years in the making prior to 1999. Another  source found on the internet
tells of  Danish beekeepers  having used this  idea since 40 years .
Insofar the  Britsh  design , called "open mesh floor"  is in action I am
not aware of.
 I do not appreciate  anyone  to seek  the credit for something which
she/he had no part in designing and having the gull to try to patent  an by
now ancient idea. But then again  ; It's not my money spent for nothing.
In any case these boards  certainly have their use and advantages  over and
above  the  detrimental influence of varroa  propagation.
Jdf