Captivated by the album, Cook snapped it up for the equivalent of €120.

“Prior to that I’d never collected anything in my life,” he tells TVP World. “But I’m a history buff, and these banknotes seemed to tell the story of the region—and given that I was writing about the economies of all these countries at the time, it all seemed to fit. The album sparked my imagination.”

Inside, a fire was lit, and over the next few years Cook set aside time during his working trips around the region to scour backstreet numismatic stores, antique dealerships and flea markets.

“I set out to collect banknotes that coincided with turning points in history,” says Cook. “The seismic events that the Central Eastern European region has seen were captured by the banknotes of the governments that prevailed, and it was these that interested me.”

Cook admits that at certain times his hobby verged on the obsessive before petering out once he started his own corporate communications firm in 2004.

“My circumstances changed,” he says. “The new business was all-consuming, and I didn’t have the time to run around looking for banknotes, nor the spare money—it wasn’t a conscious decision to stop, it just dried up.”

Cook did, though, find the time to carefully store his collection in archival polymer sleeves before packing them inside an old leather suitcase. “Then I forgot all about them,” he says.

There the story may have ended were it not for an unexpected call at the height of the pandemic.

“The head of the banknote department at the Spink auction house contacted me,” says Cook. “I’d never spoken to him before, but I guess he must have had my details from back when I was buying banknotes from Spink. He was wondering if I still had some Lithuanian notes that I had purchased, but while I never got back to him it did plant the seed in my mind about what my collection could be worth.”

Finding out, however, would not be straightforward. “The problem was, I’d completely forgotten where I’d stored them,” says Cook.

Having eventually tracked down the suitcase, Cook reconnected with Barnaby Faull, a banknote specialist who had played an integral role in Cook’s earlier acquisition of several rare finds, and Andrew Pattison of Noonans Mayfair auction house.

“I was told my collection could be ‘worth something’ nowadays,” said Cook, “but when I was told just how much I went completely silent. I couldn’t believe what I was hearing.”

Divided into 251 lots, the entire collection has been forecast to command at least €180,000 when it goes under the hammer at Noonans Mayfair on November 28.

From the collection, attention will naturally fall on the most valuable banknote of all, a Bulgarian 10 Leva Srebarni note from 1899. Touting a guide price of between €7,200 and €9,500, it was originally bought by Cook for about €475.

“It’s a printer’s archival specimen, and it’s one of only two that were ever produced,” says Cook. “I think at the time it simply wasn’t known how rare it was.”

For Pattison, it is Cook’s Bulgarian banknotes that particularly standout: “I think the notes to watch will be the early Bulgarian ones and some of the more specialized Bulgarian pieces,” he tells TVP World.

“But there’s also a set of unissued Romanian notes as well as some issued Romanian pieces in the finest condition known that should also fly—collectors are very fussy about condition, so the chance to obtain the best example of anything will often attract frenzied interest.”

Despite being staggered by the potential financial return, Cook does not feel the price has been inflated. “Let’s be clear, the high value notes really are incredibly rare,” he says. “I was introduced to them by Barnaby Faull at the height of my buying when interest in them was very low, but he urged me to focus on what I was interested in and to always try to buy the best I could afford—that advice was invaluable.”

Cook credits Faull, who currently works at Noonans Mayfair following a distinguished career at Spink, with several of his more unique finds. “He’d call me and say, ‘I've got something you might be interested in’, and that’s how I came about things like banknotes ordered by Poland’s government-in-exile during WWII,” says Cook.

Printed by De La Rue in 1939, these notes—valued between €1,200 and €1,800—feature stoic looking peasants and, on the reverse, idyllic rural scenes. While some of these notes were shipped to Poland after the war, they were never brought into circulation due to the changing political landscape and most ended up destroyed.

A pair of treasury notes from Poland dating from 1794 constitute the oldest elements of ‘the Cook Collection’ but are aesthetically eclipsed by grand looking banknotes issued during the WW1 German occupation of Poland.

It is such fleeting but momentous times that the collection spans—among others, there are notes from the Free City of Fiume, which existed between 1920 and 1924 in what is now Rijeka, Croatia, as well as the interwar Free City of Danzig (now Gdańsk, Poland) and the interwar city state of Memel (now Klaipeda, Lithuania).

With so many countries in the region impacted by a steady stream of wars, invasions, occupations, break-ups and periods of independence, Cook’s banknotes illustrate the unpredictable complexity of the region as a whole.

“The banknotes in the collection all reflect times of change,” emphasizes Cook, “but whereas I got a buzz out of reading the politics and economics that you find contained on a banknote, others will appreciate them for the historical scenes that are depicted or the beauty of the engravings.”

This point should not be overlooked. Often exquisite on the eye, many of the notes are strikingly decorated with whiskered monarchs, swooning damsels, exotic coats-of-arms, patriotic landmarks and romanticized portrayals of daily life.

As remarkable as it is that Cook was able to build his collection for so little, it is no surprise that it has now swelled in value.

“Demand has been driven by a combination of two factors,” says Pattison. “Firstly, there is renewed interest in the history of the countries in question, particularly in the pre- and early post-communist era. Secondly, enough time has passed for a new generation of collectors to become wealthy enough to indulge their passion for this history.”

For Cook, the time is right to sell. “It’s the rational thing to do,” he says. “But all of this is rather fortuitous—I never saw banknotes as an investment, I bought them because they interested me. Every note tells a chapter of a national story.”