It was a part of a set of black duofold pen / ballpen (photo attached illustrating the FP model)

My problem is that the ballpen in this style seems to be a bit scarce to say the least. So that I can begin to track one down it would help if I knew the correct name of what Im looking for (...!) Can anyone tell me what model of duofold this is? The BP had the deep chequered band around the cap base and was a push (rather than twist) action. Since Ebay seems a bit of a dead end, any recommendations for dealers?
All help gratefully received!
Regards
David
ps - Whoops - maybe should've gone in the Parker forum, but, hey...