I am particularly interested in 1985 and 1991.
It was fixed at a set rate until September 1989 - I'm not sure what it was, though. After that, it was devalued repeatedly.
nytimes.com/1990/01/01/business/devaluation-in-poland.html
gives us a figure of 9,500zl to the dollar in January 1990.
As I recall, what they did was devalue the currency repeatedly until the official rate became parallel to the black market rate - but the Zloty didn't become fully convertible outside Poland until the mid 90's at the earliest. I'm pretty certain there would have been no exchange rates for Zloty-Pound between 1985-1991 - everything would have been based on the dollar exchange rate.
Was the Zloty even traded on the open markets in 1985???
Interestingly, there appears to have been Zloty bonds traded during that time.
It was fixed at a set rate until September 1989 - I'm not sure what it was, though. After that, it was devalued repeatedly.
No. I was wrong.
The zloty was repeatedly devalued, even during Communist times - I'm finding evidence of frequent devaluations throughout the 1980's. As alex says, the USD was the currency used for any real trade.
Perhaps the best bet would be to contact the National Bank of Poland and ask them? They should be able to provide such data.
