One of Scotland’s most colourful and influential creative figures is battling to secure his artistic legacy after suffering a stroke.

Richard Demarco, 87, revealed in a newsletter to his friends and supporters that he had been unwell and that “the last two weeks have been challenging, to say the least”.

The artist and promoter said that he was now aware he “urgently” needed a team of historians, archivists and curators to secure large parts of his enormous archive of artworks and photographs. Demarco also expressed the wish that the Tate archives in London could work on a joint exhibition with the Scottish National Gallery of Modern Art (SNGMA), which already holds a fraction of the works he has collected over the decades.

In all, Demarco’s archive is thought to contain more than 10,000 paintings and drawings by artists from 50 countries, more than a million photographs, and memorabilia documenting art and artists in Scotland.

As he explained to his supporters, a substantial part of his collection is housed in seven rooms at the Summerhall arts venue in Edinburgh. Other works are on show in the library of Stewart’s Melville College.

The archive contents, however, remain a mystery — even the material Demarco has gifted to the nation — because it is so extensive that it has been difficult to catalogue, as the artist made clear.

“It would be helpful if I could have full information on what is contained in the SNGMA part of the Demarco archive,” he said. “How many artworks are there, and by whom? How many archive boxes are still to be examined? Could there possibly be an exhibition in 2018 at the gallery?”

For many people, Demarco, born and raised in Edinburgh, embodies the city’s festivals, not least because he has witnessed every festival season since its inception in 1947.

He studied at the city’s art college, where Sir Sean Connery, a lifelong friend, was a model in his life drawing class. In 1967, when he gave up his teaching job at Scotus Academy, he had already co-founded, with Jim Haynes, Edinburgh’s groundbreaking Traverse Theatre, and opened his first gallery.

Despite becoming a substantial figure on the British arts scene, Demarco, a tireless promoter of the arts in Edinburgh and around the world, has received only minimal public funding.

In his newsletter Demarco revealed that he was back at work “but with the problem of restricted use of my right hand”.

Yesterday, when The Times attempted to catch up with him, he was en route to events in Harrogate, Yorkshire, and Belfast, Northern Ireland, and was unavailable for comment.