Royal Mail has faced criticism this week after a spokesman confirmed the company had no plans to issue commemorative stamps to mark Brexit.

The foreign secretary, Boris Johnson, who backed a campaign to introduce the stamps, said: “Leaving the European Union will be a monumental moment in British history, so let’s deliver a commemorative stamp.”

Margot James, the minister responsible for postal services, confirmed she had no plans to challenge Royal Mail’s decision.

Critics of the the company have pointed out that in 1973 a series of stamps, alongside a presentation pack and first-day cover, were issued to commemorate the UK joining the European Economic Community (EEC). They say Royal Mail has produced politically divisive stamps in the past, including a collection that featured former prime ministers.

Royal Mail stamps issued in 1973 to commemorate the UK joining the EEC. Photograph: Royal Mail

Royal Mint has also previously issued coins linked to the EU. In 1998, 5m special 50ps were minted to celebrate the UK’s presidency of the bloc, and the 25th anniversary of the accession to the EEC.

The 1998 EU 50p coin issued by the Royal Mint Photograph: Royal Mint

Despite the lack of stamps, there are plenty of unofficial commemorative Brexit designs available as souvenirs – even on coins seemingly issued from the other side of the world.

A commemorative Brexit coin has been available since 2016, bearing the name of the Cook Islands. While the archipelago mostly uses the New Zealand dollar, it has made a name for itself in numismatic circles by allowing a wide variety of commemorative coins to be issued on its behalf.

Recently minted have been coins to celebrate the Fantastic Beasts and Guardians of the Galaxy movies, as well as a panda-shaped $20 coin. The Liechtenstein-based Coin Invest Trust was behind the Brexit coin, which comes in three varieties and bears a portrait of the Queen.

The 2016 Brexit coin manufactured by Coin Invest Trust and issued by the Cook Islands. Photograph: Coin Invest Trust

You can also purchase unofficial celebratory coins made in Britain. The Bradford Exchange offers two coins bearing the slogan: “The landmark vote for Britain’s independence” that depict Britannia and a lion. The largest will set you back £129.95.

The Bradford Exchange’s UK-EU referendum commemorative coin retails for £129.95. Photograph: The Bradford Exchange

Far cheaper at £4.99, an enterprising eBay seller is offering 300 limited edition Brexit coins. The design, created by the seller, draws a comparison between the Brexit vote and the signing of the Magna Carta and carries the declaration: “Never give our sovereignty away again”.

If you really must add Brexit stamps to your post, eBay offers another option – a set purporting to be issued by Central African Republic. Featuring former Ukip leader Nigel Farage, Johnson, Theresa May and a rather forlorn-looking David Cameron, the stamps appeared in September 2016.

Fake Brexit stamps which claim to have been issued by the Central African Republic Photograph: ebay

They are not official and appear to be the product of a Lithuania-based outfit that regularly produces stamps bearing the name of African countries aimed at collectors.

If you have ever wondered what motivates people to buy them, this review of a pro-Brexit keyring written by a leave voter sums it up: “Always a talking point. I really like to start conversations with like-minded thinkers and gently wind up those who are not yet on board.”