Since when? http://www.gracesguide.co.uk/Rolls-Royce_Engines:_Peregrine-
Furthermore; .
Fastmongrel, where were you getting that idea from? Because it doesn't seem, to be actually so.
It says so on Graces Guide, which you provided. The Peregrine is 80% of the Merlin. It seems obvious with the lack of applications that the Peregrine was an unwanted and unneeded engine, and since the Whirlwind was developed to escort day bombers for a force that didn't operate bombers by day, the Whirlwind too was unwanted and unneeded. Handed Peregrines, with both rotational directions by gearing, were developed for the Whirlwind, but it seems it was too much trouble to implement until it made a return on the Merlin 130s which powered the DH Hornet. Production Whirlys didn't get handed props. By 1941, the Whirly/Peregrine, undeveloped, had lost its performance edge.