Keith,
The ORB (Form 540) for 328 Sqn.(GC 1/7) shows Perrier intercepting a Me 410 at 26,000 ft.(?) on April
20. Because of the 'watermark' in the online viewer it's difficult to read (written in French) but, as best I can make out, it seems that Perrier's guns malfunctioned and no claim was made. I could be wrong. You can of course download the ORB and get a better view.
http://discovery.nationalarchives.go...ils/r/D8401596
Interestingly there is no mention of this in the Form 541 for that date. Perrier is not even listed as flying on April 20.
http://discovery.nationalarchives.go...ils/r/D8401597
Best wishes,
Tom