They have been turned into florists, libraries, cafes - and even a mobile phone repair shop.
Now, one of the iconic red telephone boxes - designed by Sir Giles Gilbert Scott - has been turned into London's smallest art gallery.
St Johns-Wood raised artist Degard bought one opposite The British Museum in 2021 and turned it into a showcase for 'visionary art'.
"To fund my artistic life I buy property, and when I looked at the cheapest thing on the list it happened to be a phone box which I bought for £31,000," she says.
"I had long wanted a central London gallery and it seemed an economic and fun way of getting a little presence in central London."
Exhibitions are free and have ranged from work by Max Ernst and Suzanne Treister to a Christmas show by 12 artists, and a solo show by a taxidermist.
"We had a fox in there," adds Degard, who has lived around Golders Green and Highgate before settling in Hertfordshire.
"I am acting as a catalyst for an art movement, revitalising visionary art which hasn't been developed as a genre, and encouraging anyone with a visionary bent to show in the space.
"There's a huge footfall because of the British Museum, my gallery is almost part of the museum experience - and having a photograph taken outside a phone box is part of the London experience."
The former North West London Jewish Day School pupil is an outsider artist who didn't pick up a brush until the age of 20.
"I had a freaky Friday moment with an artist friend. I was studying at Edinburgh University writing poetry, he said: 'I would love to be a poet', I said 'I would love to be a painter'. We swapped and I have not stopped painting since."
She went on to complete a foundation at City Lit and study at Chelsea College of Art, practicing a technique that she calls "channelling auras".
"I channel from some kind of energetic place or presence onto a surface."
Starting on April 7, the exhibition The Visionary Wall - Meeting my Ancestors Lost in The Holocaust is inspired by Degard's Jewish family. In addition to grandmother Gerda, who arrived in England from Amsterdam with 'just the coat on my back and 50p in my pocket,' Degard discovered a maternal relation Charlotte Rummelsburg who threw herself from a Berlin window in 1934 amid anxiety over the rise of anti-Semitism.
Further tragic revelations followed.
"I started to investigate this relationship with my ancestors, I knew I had some relations caught by the Holocaust, but when I started to discover who they were it went from 1, to four, to 21, including two great-grandfathers, aunts, uncles and cousins. I thought I would like to bring them back to life."
With no surviving photographs of her relatives, Degard has painted their auras against the backdrop of Jerusalem's Wailing Wall; spotlighting "the context of why they didn't live their lives."
"It's extraordinary because nobody knows them or has remembered them, but channelling is a wonderful process that enabled me to meet them. They appear as I am doing the painting. I am experiencing them, understanding who they are, their thoughts and personalities. I can suddenly see a portrait of them through the paint and colours."
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