Starting in the early 1960's a group of experimenters was formed consisting of:-
Beowulf Cooper, Harrison Ashforth, John Inchley, John Cox, A friend of John Cox that I have not been able to identify, Ben Gilman, A friend of Ben Gilman, Richard Smailes, Adrian Waring, Brian Cramp and during the latter part of the experiments... Albert Knight.
The experiment was conducted during the 1960s in order to establish the productivity of bees raised in larger cells than was considered normal at the time, this project had a secondary aim of establishing the suitability of the larger cells for the Apis mellifera mellifera type bees, favoured by BIBBA.
Brian Cramp is my main contact in this case... He lives locally and we both attend meetings of the Leicestershire & Rutland B. K. A. regularly. I knew about the group when it was in existence, but did not take part in it myself. Only four of the group were still alive in 2005, but the principle revolved on longer tongue lengths of larger bees reaching the parts of nectaries that were out of reach to 'normal' bees.
Many claims of high honey yields were made, but the large cells were difficult to maintain as the bees would only draw out the larger cells if forced to by specially prepared foundation.
The part of the project that was conducted in Leicestershire was compromised by a vindictive apiary manager that did not agree with the experiment. He sabotaged the whole thing by introducing foundation of 5.45 mm size.
There is some mention of the experiment in a BIBBA magazine article by Philip Denwood.
Philip Denwood and Brian Cramp both have leaf presses from the batch of those made using 5.9 mm cell sized foundation as the original former, I wonder how many others are still in use, possibly with the owners not even realising that the presses produce foundation of the large cell variety.