I TEND to forget what's on the T-shirt I'm wearing. But there was one that always reminded me - particularly when I was in the Amazon more than 10 years ago - because people would smile and say: 'That's it! That's it!' The T-shirt soon wore out, but the memory of it returned when I was editing the June 2004 edition of this magazine about co-operatives. The image would, I felt, make the perfect front cover. But, as with most icons, it had usually been used without attribution, and it proved impossible to track down the artist in time to ask for permission.

Soon after the magazine was published I received a message from a subscriber saying that the image had been created by the artist Ken Sprague - an unheralded genius. He had dreamt up the idea while trying to communicate with banana workers in the Canary Islands - the big black fi sh was General Franco, the Spanish dictator who was still in power at the time. Having discovered this, I promptly called Ken on the telephone to apologise. Without a trace of anger, a gentle voice said that this was the fi rst time anyone had bothered to do so, and for that at least he was grateful.

A few weeks later I heard that Ken Sprague had died, aged 77, after a long and intriguing life that is celebrated in a wonderful book by John Green, Ken Sprague - People's Artist (Hawthorn Press in partnership with Artery Publications, 2002, www.hawthornpress.com). Though it is foolish not to credit the inspiration on which we rely, and too late now to make a difference, it would be more foolish still not to celebrate the richness of his legacy with a small sample of his work from that book.

The fruits of labour (above). A hand-painted sign above Sprague's studio read: 'It's not a question of an artist being a special kind of person, but of every man, woman or child being a special kind of artist.'

'An Educated Mother is the Key to a Bright Future' (inspired by a poster on a wall in Baghdad). Sprague was invited to Iraq in 1981 as an offi cial artist in the war with Iran. He went to the front and came close to being killed. Though criticized at the time for his apparent identifi cation with the regime, he maintained that he identifi ed with the people, not with the regime.

'Political to most people means political parties, corruption, insincere rhetoric and sloganizing. But to me it is more about human relationships. Whether I am producing posters for the trade unions, Save the Children Fund, Christian Action or the local Quaker group, that is, for me, politics.' Ken Sprague

The imprisoned voice (comment on oppression in Latin America). A long-standing member of the Communist Party, Sprague experimented with 'socialist realism' but quickly abandoned the attempt. 'It was like smoking; I was never a smoker because when I tried I became sick.'

'In essence, the leitmotif of his work is about power and the abuse of power as well as the resilience of ordinary working people to this abuse... It is an art of engagement - engagement for change.' John Green, from the Introduction to Ken Sprague - People's Artist, Hawthorn Press in partnership with Artery Publications, 2002, www.hawthornpress.com

Flower pot. Sprague called some of his images 'anti-tank statements directed at all those people who rush in all too quickly to solve the world's problems with guns'.

Middle-aged Romantic. Inspired by the muralist movement, Sprague travelled to Mexico to see the famous 'walls of fi re'. This caricature is a self-portrait.

Le Pen. A response to the rise of the fascistic Front National in France. In 1946 Sprague took part in a bungled attempt to kidnap the British fascist, Oswald Mosley, in Bournemouth.