I was fortunate enough to be given a Parker Duofold pen / biro set by a friend who knows I am an FP user / enthusiast, I had a look and advised him that it is probably quite valuable and I have offered to give him some money to use as a charitable donation in return.

I am hoping some of the knowledgeable people on here can give me an idea of value, personally I am more an enthusiast for modern Japanese FP's and don't own any premium Parker pens other than vintage 51's. Here are some photos and details :

Set comes in a wooden box with Parker Duofold stamped on the top and is a white-marble resin patterned fountain pen and matching biro in a wooden box. The FP is a cartridge filler and 13.6 cm long including cap, M nib is labelled PARKER 18 750, the black cap has PARKER MADE IN UK in small writing. I don't see any other distinguishing features, but would guess from conversation was purchased around 1990.

I have looked here and think it is possibly a Duofold international, can anyone help out with identification and thoughts on approx value? (I have no intention of selling but will help me decide how much to donate)

More photos here if you want, they are quite big :

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